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Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate the tool is not read-only (readOnlyHint=false) and not destructive (destructiveHint=false). The description adds that it sends a follow-up and explains modes, but does not disclose return behavior, whether it blocks, or how to monitor progress. It mentions opening a PR as a side effect, which adds behavioral context. No contradictions with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two paragraphs: first defines purpose and key use case (open PR), second explains the two modes. It is concise and front-loads the most important information. Could be slightly more structured (e.g., bullet points), but no unnecessary sentences.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With 6 parameters and no output schema, the description covers the main purpose and delivery modes. However, it lacks explanation of return behavior, asynchronous nature, or how to combine with sibling tools like capy_wait for completion. The PR opening mention adds context but leaves details unspecified.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3. The description adds value by explaining the 'mode' parameter's effect (interrupt vs queue) and the workaround for opening PRs. It does not elaborate on other parameters like model, reasoning, or build_model beyond what the schema provides, but the schema already describes them well.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool sends a follow-up instruction to an existing Capy thread and enumerates specific use cases (steer, answer questions, correct approach, request more work, open PR). This distinguishes it from sibling tools like capy_open_pr (which has no endpoint, so this tool is the workaround) and capy_status or capy_list.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit guidance on when to use the tool (sending follow-up instructions, including opening PRs) and explains the two delivery modes ('interrupt' vs 'queue') with their appropriate contexts. It does not explicitly compare to siblings like capy_stop or capy_delegate, but the context is clear enough for an agent to infer usage boundaries.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.