Option B identifies the missing executable capability. Defining specialized agents makes their configurations available, but the coordinator must still be permitted to call the tool that invokes them. Without that tool, Claude can describe an intended delegation in ordinary text but cannot create a subagent execution.
The current Claude Agent SDK documentation requires " Agent " in allowedTools to auto-approve subagent invocations. The tool was renamed from " Task " to " Agent " in Claude Code 2.1.63, so the terminology in the original candidate question required correction. Older integrations may still expose " Task " in initialization or permission records.
Option A is unlikely because properly written AgentDefinition.description values already tell Claude when each agent should be used. Option C misinterprets context isolation: the parent supplies the subagent's assignment through the Agent tool's prompt, and no additional automatic forwarding setting is required.
Option D would normally produce truncation evidence or a max_tokens stop reason rather than silent absence of every invocation. The coordinator needs both agent definitions and permission to use the invocation tool.

Option B removes ambiguity at the tool-interface level. Extraction, summarization, and claim verification are different operations with different success criteria and output structures. Separate tools allow each operation to have a precise name, purpose, parameter schema, response contract, and error behavior. Anthropic's guidance on writing effective tools for agents recommends a small set of thoughtful tools targeted at specific, high-impact workflows rather than generic wrappers that force the model to infer operational meaning from loosely structured instructions. Tool descriptions and examples, option A, could improve behavior but leave the overloaded free-text contract intact. An analysis_type enum, option C, identifies the requested mode but still requires one tool to return substantially different result structures, increasing validation and downstream branching. Coordinator pre-classification, option D, adds another probabilistic decision without correcting the interface used by the analysis agent. Purpose-specific tools let the synthesis layer know exactly what output it will receive. Their schemas should require relevant fields-for example, data-point names and source locations for extraction, or claim, verdict, and evidence for verification-and should be tested against the observed failure cases.

The decisive trade-off is whether the workflow can tolerate asynchronous completion. Anthropic's Message Batches API documentation states that batch requests receive a 50% discount and that most batches finish within one hour, but processing can continue for as long as 24 hours. Therefore, the review process is suitable for batching only if potentially delayed feedback remains useful.
Option C directly tests that operational requirement. The reviews are already non-blocking, which makes batching promising, but non-blocking does not automatically mean that feedback delivered many hours later still has value. If developers have already merged and moved to unrelated work, delayed security findings may increase remediation cost or remain unaddressed.
Option A is manageable through each request's unique custom_id, which allows results to be correlated regardless of return order. Option B is incorrect because batch requests can contain supported multi-turn conversation histories and tool-use configurations; each request is processed independently, but it need not represent a single conversational turn. Option D reverses the relevant consideration: batch processing is not intended to provide near-instantaneous responses. The real question is whether the cost saving justifies its longer and nondeterministic completion time.

Option C identifies the fundamental trade-off introduced by batch processing: lower cost in exchange for asynchronous completion and potentially substantial latency. Anthropic states that most Message Batches complete within one hour, but results may become available only when all requests finish or after 24 hours, whichever occurs first. Therefore, the workflow must remain useful even if security findings arrive considerably later than they would through synchronous requests.
The reviews are explicitly non-blocking, so batch processing can be suitable if developers can still act on delayed findings through follow-up commits. Option B describes an implementation requirement because batch results may be returned out of submission order, but Anthropic provides a deterministic solution through each request's unique custom_id. Option A incorrectly focuses on near-instant feedback, which batch processing does not provide. Option D is not decisive because batches support independent Messages API requests containing system prompts, tool use, and multi-turn conversation content. The primary decision is therefore whether the maximum practical feedback delay is acceptable to the development workflow.
Anthropic Message Batches documentation

Option C corrects the weak selection signal presented to the model. Claude chooses among available tools using their names, descriptions, parameter schemas, and the current request. "Extracts a function from code" does not explain whether the tool understands syntax trees, preserves imports, updates call sites, validates scope, or offers advantages over Write and sed. Anthropic identifies prompt-engineering tool descriptions as one of the most effective ways to improve agent tool use. Descriptions should state what the operation performs, when it should be selected, what inputs are required, what output it returns, and any limitations.
Option A adds a separate probabilistic routing layer without improving the tool contract Claude ultimately sees. Option B ignores the server's intended value. Option D removes a broadly useful capability and may prevent unrelated edits without guaranteeing that the MCP tools are used correctly. Each refactoring tool should instead describe its semantic behavior and contrast it with plain text manipulation-for example, that rename_variable performs scope-aware symbol renaming and updates references. Clear schemas, concrete examples, and evaluation against real refactoring tasks should accompany the improved descriptions.