CCAR-F Claude Certified Architect – Foundations Question and Answers

The primary risk is not implementation difficulty but incomplete requirements. Production caching introduces decisions involving invalidation, stale-data tolerance, cache keys, tenant boundaries, serialization, stampede prevention, failure behavior, observability, deployment topology, and consistency expectations. Implementing Redis with a five-minute TTL before resolving these questions can produce a technically functional but operationally unsafe design.

Anthropic recommends having Claude interview the user before beginning a larger feature when important requirements remain uncertain. The AskUserQuestion workflow is intended to surface technical implementation concerns, edge cases, trade-offs, and assumptions the user may not have considered. Anthropic further recommends converting the resulting answers into a self-contained specification with explicit scope and an end-to-end verification step. ( https://code.claude.com/docs/en/best-practices )

Option B provides useful codebase context but postpones requirement discovery. Option C creates avoidable rework by allowing architecture to emerge from production failures. Option D documents uncertainty but delegates unresolved design choices during implementation, when they may already constrain the code.

After the interview produces a caching specification, Claude can enter plan mode to inspect the endpoint and map those requirements onto the existing architecture before implementation.

Official references/topics: Requirements Interviewing; AskUserQuestion; Specification Development; Edge-Case and Trade-Off Discovery.

The search must first establish the function’s complete naming surface. Reading the core definition and every wrapper or re-export reveals aliases such as computeOrderTax , names introduced through intermediate modules, and potentially different import paths. Once those names are known, the agent can search the entire codebase for each exposed identifier and inspect the resulting call sites.

Claude Code’s Grep tool searches patterns inside file contents, whereas Read provides the surrounding implementation needed to determine whether a wrapper delegates to, renames, or conditionally invokes the original function. These tools are complementary: Read establishes semantic identity; Grep provides broad reference discovery. ( https://code.claude.com/docs/en/tools-reference?utm_source=chatgpt.com )

Option B misses every caller using a wrapper alias. Option A may find importing files, but import-level discovery is indirect and can miss re-exports, namespace imports, dependency injection, or calls made through a locally renamed symbol. It also requires unnecessary manual inspection of every consumer of the module. Option D relies on documentation, which may be incomplete or stale and cannot prove that all executable references have been found.

Before removal, the agent should also inspect tests, dynamic registrations, configuration-driven references, and generated code where relevant. The defining requirement is to map the alias chain first and then search all discovered public names.

Official references/topics: Read and Grep Tool Behavior; Symbol and Alias Discovery; Codebase Reference Tracing.

The Messages API exposes stop_reason specifically so the application can determine why Claude stopped generating and what action is required next. A value of tool_use means Claude is requesting one or more tools and expects the application to execute them and return corresponding tool_result blocks. A value of end_turn means Claude has naturally completed the response. ( https://platform.claude.com/docs/en/build-with-claude/handling-stop-reasons )

Anthropic’s agent-loop tutorial implements this as a loop that continues executing tools and returning results while stop_reason remains tool_use . Once the value changes, the response is treated according to the new terminal or continuation condition. ( https://platform.claude.com/docs/en/agents-and-tools/tool-use/build-a-tool-using-agent )

Option A is unreliable because an assistant response can contain both text and tool-use blocks. Text alone does not prove that the workflow is complete. Option B requires the application to predict that no further tool call is needed, defeating Claude’s ability to adapt from tool results. Option D is an important safety limit but is not the primary completion signal; an arbitrary maximum may terminate a valid workflow prematurely.

The harness should check stop_reason , process every requested tool call, append results to the conversation, and maintain a separate maximum-turn safeguard against runaway loops.

Official references/topics: Messages API stop reasons, tool-use loops, tool-result continuation, bounded orchestration.

Retry-with-error-feedback is effective when the required information is available and the defect concerns representation. Options A, C, and D are correctable formatting failures: the model can flatten an object into an array, remove thousands separators and emit an integer, or convert a datetime into the required date-only format. The validation message supplies enough information to revise the output.

Option B is fundamentally different. The complete co-author list is absent from the model’s input and exists only in an external document. No number of retries can recover evidence that was never supplied. Repeated attempts may instead increase the probability of fabrication. Anthropic’s hallucination guidance recommends restricting responses to available documents, allowing the model to acknowledge missing information, and withholding or retracting claims that cannot be grounded in the source. ( https://docs.anthropic.com/en/docs/test-and-evaluate/strengthen-guardrails/reduce-hallucinations )

The correct response is therefore to return an explicit missing-data state, retrieve the external document through a tool, or route the record for enrichment. Retrying without changing the information boundary cannot solve the problem.

Current Anthropic Structured Outputs can eliminate many shape-related failures by guaranteeing JSON Schema conformance, but they still cannot create unavailable source facts. ( https://platform.claude.com/docs/en/build-with-claude/structured-outputs ) This distinction—format failure versus evidence failure—is central to reliable extraction architecture.

Official references/topics: Retry Boundaries; Missing Context; Grounded Extraction; Structured Outputs; External Data Retrieval.

MCP allows a Claude application to connect to multiple servers and expose their enabled tools within the same agentic interaction. Anthropic’s MCP connector documentation explicitly supports connecting to multiple MCP servers in one request. Once connected, Claude can invoke a server’s tool when the user’s request corresponds to the capability described by that tool. ( https://docs.anthropic.com/en/docs/agents-and-tools/mcp-connector )

In this scenario, the git server can provide the branch-creation operation, the documentation server can locate the relevant links, and the Jira server can update ticket JIRA-123. The agent can coordinate these capabilities without requiring a separate conversational turn that restricts it to only one server. Tool descriptions and schemas tell Claude what each operation does and what inputs it requires.

Option B incorrectly describes sequential capability discovery. Server identity and tool definitions are established through the MCP configuration rather than discovered by querying every server for each operation. Option C is incorrect because connecting several servers does not inherently restrict the agent to a single selected server. Option D imposes a one-server-per-turn limitation that MCP does not require.

Access can still be controlled through allowlists, denylists, permissions, and per-tool configuration. Those controls restrict which tools are enabled; they do not change the fundamental ability to make tools from multiple configured servers available together.

Official references/topics: MCP Server Configuration, Multi-Server Tool Access, Tool Discovery, MCP Tool Permissions.

The pipeline must preserve source evidence while making inconsistencies explicit. Option D records the amount stated on the invoice separately from the total derived from extracted line items. A mismatch then becomes a machine-detectable validation condition rather than an invisible extraction defect.

This approach is superior because it does not silently overwrite source data or ask another model to guess which value is correct. Anthropic’s evaluation guidance recommends automated, code-based grading whenever the criterion can be expressed deterministically. Arithmetic reconciliation is precisely such a criterion. ( https://docs.anthropic.com/en/docs/build-with-claude/develop-tests ) In production, the summation should preferably be calculated by application code using normalized decimal values, even though the option describes the model populating calculated_total . The essential design principle remains the same: preserve stated_total , compute an independent total, compare them, and route discrepancies for adjudication.

Option A might improve behavior but cannot resolve genuine OCR corruption and could encourage the model to modify extracted values merely to create mathematical consistency. Option B introduces a second probabilistic judgment without new evidence. Option C is unacceptable for accounting data because it fabricates adjusted amounts and destroys fidelity to the invoice.

The schema should therefore expose both values and attach a validation status or review reason when they differ.

Official references/topics: Deterministic Validation; Human-in-the-Loop Review; Structured Output Design; Source-Fidelity Controls.

Option D separates durable case history from volatile operational data. The new session receives a compact, structured summary describing the billing dispute, the customer’s objective, actions previously taken, and the unresolved status. It does not inherit outdated backend observations as though they were still authoritative. Fresh tool calls then retrieve the current refund or order state before the agent responds.

Agent SDK sessions preserve conversation history, including earlier tool calls and tool results. Resuming the complete transcript therefore reintroduces stale system data into the active context, even though the external backend may have changed substantially during the four-hour gap. Conversation persistence must not be confused with persistence of external-system truth.

Option A performs unnecessary calls to every previously used tool, including tools unrelated to the returning customer’s current question. Option B relies on prompt compliance while retaining contradictory historical evidence in context. Option C manually removes tool results from an existing transcript and may damage the logical relationship between prior tool_use and tool_result blocks while still retaining a long, unstructured conversation.

A structured summary should preserve stable identifiers, previous actions, customer commitments, and unresolved issues. Time-sensitive fields such as refund status, delivery state, account balance, or expected resolution should always be refreshed through authoritative tools.

Official references/topics: Session persistence, stale tool-result management, context compaction, fresh-data retrieval.

Limited review capacity should be concentrated on records with the highest probability of semantic error. Schema validation confirms that the response has the correct structure and data types; it does not establish that the extracted values are accurate. Ambiguous wording, contradictory passages, missing evidence, and model-reported uncertainty are direct indicators that an extraction requires human judgment.

Anthropic’s reliability guidance recommends permitting Claude to express uncertainty, grounding factual outputs in source material, and validating critical information because hallucination-reduction methods do not eliminate errors completely. These principles support routing uncertain or evidentially conflicted records to reviewers rather than treating syntactically valid output as automatically trustworthy. ( https://docs.anthropic.com/en/docs/test-and-evaluate/strengthen-guardrails/reduce-hallucinations )

Option B may waste reviewer capacity on clear, well-supported values while overlooking ambiguous errors in other fields. Option C is reactive: downstream acceptance does not guarantee semantic correctness, and silent errors may never produce processing failures. Option D provides an unbiased estimate of overall quality and should be retained as a secondary audit mechanism, but random selection is not the most efficient way to intercept risky records when only 5% can be reviewed.

In production, model confidence should not be treated as a calibrated probability by itself. It should be combined with objective signals such as contradictory source spans, missing citations, OCR quality, validation warnings, document type, and business impact.

Official references/topics: Human-in-the-Loop Review, Uncertainty Handling, Source Grounding, Risk-Based Escalation.

Resuming preserves the prior architectural analysis, dependency mapping, and conversation history, avoiding the cost of repeating an hour of valid work. Anthropic states that resuming by session ID restores the agent’s full prior context, including files read, analysis performed, and decisions made. ( https://code.claude.com/docs/en/agent-sdk/sessions )

However, the session represents historical knowledge rather than a repository snapshot. Because three files changed externally, the agent must be told which files are affected and directed to re-read them before relying on earlier conclusions. Anthropic clarifies that sessions persist the conversation, not the filesystem. ( https://code.claude.com/docs/en/agent-sdk/sessions ) Targeted re-analysis updates the stale portion of the agent’s model while retaining the nine unchanged files’ established context.

Option A discards valuable work even though most of the analyzed code remains unchanged. Option C is accurate but inefficient because it reprocesses all twelve files regardless of whether they changed. Option D is unsafe: the agent may continue reasoning from obsolete function signatures, dependencies, or control flows.

The continuation prompt should identify the changed files, summarize the merge’s purpose where known, and request a focused comparison against the earlier understanding. Any architectural conclusions affected by those changes should then be revised explicitly.

Official references/topics: Session Resume; Filesystem Versus Conversation State; Targeted Re-Analysis; Repository Change Awareness.

The task is open-ended because neither the critical modules nor the required testing sequence is known in advance. The agent should first use lightweight discovery tools to map the repository, locate existing tests, identify central modules, and determine which components have high fan-in, business significance, complex branching, or extensive external dependencies. It can then produce an initial risk-based testing plan and refine it as new dependency information appears.

Anthropic distinguishes predefined workflows from agents that dynamically control their processes and tool usage. Agents are appropriate when the required steps cannot be reliably hardcoded and must adapt to environmental evidence. During execution, they should obtain ground truth through tool results and use that feedback to determine subsequent actions. ( https://www.anthropic.com/research/building-effective-agents ) Anthropic also identifies orchestrator-worker designs as suitable for complex coding and search tasks where the necessary subtasks depend on what the investigation reveals. ( https://www.anthropic.com/research/building-effective-agents )

Option A assigns effort using directory boundaries rather than risk. Option C exhausts context before delivering value. Option D uses alphabetical order, which has no relationship to impact or coverage priority.

Option B establishes an evidence-driven decomposition: discover, prioritize, test high-impact paths, measure results, and revise the plan as dependencies and uncovered risks emerge.

Official references/topics: Dynamic Task Decomposition; Adaptive Agent Loops; Orchestrator-Workers; Risk-Based Test Planning.

The agent must preserve durable state for several concurrently open issues without keeping every conversational turn in the active context window. Option D creates a structured issue ledger containing identifiers, issue type, requested action, current status, completed steps, unresolved questions, and relevant tool outputs.

Anthropic recommends structured note-taking for long-horizon agents. In this pattern, critical state is written outside the context window and retrieved later, allowing the agent to preserve dependencies and progress across dozens of tool calls. Anthropic also describes compaction as retaining critical details while discarding redundant raw messages and historical tool output. ( https://www.anthropic.com/engineering/effective-context-engineering-for-ai-agents )

Option A is better than retaining the entire transcript, but a narrative summary can merge separate issues or obscure exact identifiers and statuses. Option B will discard the refund conversation because it occurred outside the most recent 30 turns. Option C may recover current backend facts, but it cannot reconstruct conversational commitments, prior explanations, or why a particular action remains pending.

A structured context layer should maintain one record per issue and be updated after every material action. The active prompt can include compact summaries of all open issues and expanded details only for the issue currently being discussed.

Official references/topics: Structured note-taking, external agent memory, context compaction, multi-issue state management.

The root cause is an incomplete tool contract. Claude sees that process_refund requires an order_id , but the tool description does not explain the parameter’s trusted source or the prerequisite lookup sequence. Option A makes the dependency explicit and prohibits fabricated values.

Anthropic states that tool descriptions should explain what a tool does, when it should be used, how it behaves, and any important limitations. Its prompting guidance also states that dependent tool calls must be executed sequentially and that Claude must never use placeholders or guess missing tool parameters. ( https://platform.claude.com/docs/en/agents-and-tools/tool-use/define-tools )

Option B merely forces some tool use; it does not force the correct tool or prevent a fabricated identifier. Option C is an essential defense-in-depth control, but it detects the invalid ID after the model has already made the faulty call. It does not correct the selection logic that caused the fabrication. Option D works only when the customer actually provides an identifier and introduces an unnecessary preprocessing dependency.

The process_refund schema should describe order_id as a verified identifier returned by lookup_order , and the tool description should state that the tool is unavailable until the corresponding order has been retrieved and eligibility established.

Official references/topics: Tool descriptions, prerequisite tool calls, parameter provenance, sequential tool orchestration.

In the standard Claude tool-use loop, the application executes lookup_order and sends its output back as a tool_result . That result becomes part of the conversation state available to Claude. Claude then evaluates the purchase date, refund policy, customer request, authorization constraints, and available tools before selecting the next action.

Anthropic describes client-tool orchestration as a repeated loop: Claude emits a tool_use request, the application executes it, returns a tool_result , and Claude continues reasoning from the updated conversation. Claude, rather than the tool implementation, selects when and how to invoke the next available tool unless the application has explicitly implemented a fixed workflow. ( https://platform.claude.com/docs/en/agents-and-tools/tool-use/how-tool-use-works )

Options B and C describe possible custom orchestration architectures, but neither is stated in the scenario. Option D is inconsistent with adaptive agent behavior because later actions depend on information that did not exist before lookup_order completed. A rigid sequence would not respond appropriately to different purchase dates, eligibility states, or order conditions.

The tool result should return high-signal fields such as purchase date, return-window status, refund eligibility, existing refund status, and stable order identifiers so Claude can make the subsequent decision accurately.

Official references/topics: Tool-result continuation, adaptive agent loops, model-directed tool selection, sequential dependency handling.

The venue server must be available to every project contributor, so it belongs at project scope. Claude Code stores project-scoped MCP configurations in the repository-root .mcp.json file, which can be committed to version control and shared with the team.

The experimental playlist server should remain private. Local-scoped MCP servers are stored under the current project’s entry in ~/.claude.json , while user-scoped servers are also stored in ~/.claude.json but load across all projects. Because this server is described as a personal experiment, either private scope is conceptually appropriate; among the listed choices, option B correctly separates shared project configuration from private personal configuration. ( https://code.claude.com/docs/en/mcp )

Option A prevents the team from receiving the venue configuration. Option C reverses the intended visibility. Option D exposes the experimental server configuration to other contributors and may commit machine-specific commands or credentials.

The preferred commands would specify --scope project for the shared venue server and --scope local for an experiment limited to the current repository. Project-scoped servers also require user approval before Claude Code activates configurations received through .mcp.json .

Official references/topics: MCP Installation Scopes; Project Scope; Local Scope; .mcp.json ; ~/.claude.json .

The implementation approach is unresolved and carries architectural consequences. WebSockets, Server-Sent Events, and polling differ in connection lifecycle, bidirectional communication, proxy compatibility, scaling requirements, deployment topology, reconnection behavior, and operational complexity. Claude should therefore inspect the existing application and infrastructure before modifying code.

Anthropic recommends separating exploration and planning from implementation when the approach is uncertain, the work affects multiple files, or the developer is unfamiliar with the relevant architecture. In plan mode, Claude can read files and analyze the system without making changes, produce a detailed proposal, and allow the developer or team to review the plan before execution. ( https://code.claude.com/docs/en/best-practices )

Option A commits to polling before determining whether its latency and load characteristics meet the requirement. Option B delegates a consequential architectural decision and immediate implementation to a single execution step without a review checkpoint. Option D prematurely selects the most infrastructure-sensitive option and assumes later refactoring will be inexpensive.

Option C creates the correct sequence: examine the frontend and backend architecture, document requirements, compare alternatives, identify infrastructure constraints, obtain approval, and only then implement the selected design with appropriate tests and observability.

Official references/topics: Plan mode, explore–plan–implement workflow, architectural trade-off analysis, review checkpoints.