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

The description reveals critical behavior not visible in annotations: the opener is automatically broadcast as the first message in every new conversation, and only once per new session. It also discloses content restrictions (no AI/auto-send markers, no contact links, sensitive-word filtering), maximum length, and terminal error codes. No contradiction with annotations; idempotentHint and openWorldHint align with the described semantics.

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?

Though long, the description is tightly organized with clear headers and every section carries operational value. The most important behavior (auto-send, broadcast nature) and hard constraints are front-loaded, and there is no filler or repetition.

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?

For a one-parameter setter with no output schema, the description supplies complete context: prerequisites and composition chain, side effects, reset behavior via null/empty, validation limits, error handling, and content policy. Nothing an agent needs to call this correctly is missing.

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 the baseline is 3. The description goes beyond the schema by providing substantive content rules for the opener value: be concrete, avoid unverifiable claims, avoid template-sounding phrases, mention where you saw the user, and never include AI disclaimers or contact info. This materially helps the agent construct a valid, high-quality parameter value.

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's function: writing a personalized automatic opener that is sent as the first message when someone starts a conversation with the user. It differentiates this from get_my_chat_opener (reviewing the current opener) and frames it as a copywriting task, not a generic setter.

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?

A dedicated '何时用' section explicitly identifies this as a pure copywriting task the agent should perform. The composition chain (get_my_card → set_my_chat_opener → get_my_chat_opener → start_conversation) gives clear workflow guidance, and the description routes contact-information requests to request_contact_exchange, providing an explicit alternative.

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