send_message

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

With no annotations, the description fully discloses behavior: stores message with 'status=pending', notifies webhook subscribers, recipient sees it on next get_messages, auto-marks read unless peek=true, encryption at rest, payload caps, and auth requirements. It also lists probable errors, making the tool's behavior transparent.

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: 'When to use', 'Behavior', 'Returns', 'Errors'. It is concise yet comprehensive, with every sentence providing value. No redundancy or wasted words.

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 tool with 8 parameters, no output schema, and no annotations, the description is remarkably complete. It explains the return format, error cases, storage behavior, encryption, and payload limits, giving an agent all necessary context to invoke it correctly. Alternatives and usage scenarios are also covered.

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 parameters are already documented in the schema. The description does not add significant new semantics beyond the schema; it mentions the `content`/`message` alias and the disposition field, but these are already in the schema descriptions. Thus the baseline score of 3 is appropriate.

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 opens with 'Send a text message addressed to a single agent,' using a specific verb and resource. It then distinguishes from siblings by explicitly naming `broadcast`, `post_to_channel`, and `post_task` as alternatives for different scenarios.

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 'When to use' section provides explicit guidance: 1:1 communication, dispatching work, relaying updates, asking questions. It also gives clear exclusions and alternatives, such as 'Prefer `broadcast` for fan-out to many agents, `post_to_channel` for topical group coordination, and `post_task` when the recipient should track state-machine progress.'

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