feishu_im_user_message

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behavioral traits: the tool acts with user identity ('以用户身份发送消息'), has security constraints requiring user confirmation, includes idempotency handling via the uuid parameter, and specifies content format requirements. However, it doesn't mention rate limits, error handling, or response formats, leaving some gaps in behavioral context.

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 well-structured with clear sections (usage guidelines, actions, important notes, security constraints) and uses bold text for emphasis. Most sentences earn their place by providing essential information, though some redundancy exists (e.g., content format is mentioned multiple times). It's appropriately sized for an 8-parameter tool with complex requirements.

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?

Given the tool's complexity (8 parameters, no annotations, no output schema), the description provides substantial context: usage rules, action explanations, parameter guidance, and security constraints. It effectively covers the tool's purpose and critical behavioral aspects. However, it lacks details on error responses, rate limits, and specific output formats, which would enhance completeness for such a multifaceted tool.

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?

The schema description coverage is high (88%), so the baseline is 3. The description adds significant value beyond the schema by explaining parameter semantics in context: it clarifies that 'receive_id_type=open_id' is for private chats and 'receive_id_type=chat_id' for group chats, provides critical guidance on content format ('content 必须是合法 JSON 字符串'), and emphasizes the uuid parameter's idempotency role. This compensates well for the 12% schema coverage gap.

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 purpose: '飞书用户身份 IM 消息工具' (Feishu user identity IM message tool) with specific actions 'send（发送消息）' and 'reply（回复消息）'. It explicitly distinguishes from sibling tools by stating '当没有明确要求时优先使用message系统工具' (when not explicitly requested, prioritize using the message system tool), which helps differentiate it from other messaging tools in the sibling list like sendMessageFeishu and replyMessageFeishu.

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 usage guidelines: '有且仅当用户明确要求以自己身份发消息、回复消息时使用' (use only when the user explicitly requests to send or reply to messages as themselves) and '当没有明确要求时优先使用message系统工具' (when not explicitly requested, prioritize using the message system tool). It also specifies security constraints requiring user confirmation before use, clearly defining when to use this tool versus alternatives.

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