message_history

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

Annotations declare readOnlyHint=true, and the description adds meaningful behavioral context: who, when, the note/reason, ordering (oldest first), and the special rule that a work_status passed to send_message is recorded as a sender transition. This goes beyond the schema without contradicting the annotation.

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?

Two sentences with zero filler, front-loaded with the core concept and a valuable non-obvious detail about send_message. Every sentence earns its place.

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 one required integer parameter, a readOnlyHint annotation, and an output schema present, the description covers event types, ordering, actors, and a special edge case. Nothing critical for correct invocation 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 0%, but the description supplies the referent — 'for a message' — making the single integer message_id unambiguous. It doesn't spell out format or validity, but for a single required parameter the added context is sufficient.

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 verb and resource ('Audit trail of lifecycle events for a message') and enumerates specific event types (resolve/reopen/work_status transitions, body revisions, supersedes). This differentiates it from siblings like get_thread or pin_history without needing to inspect their schemas.

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 implies when to use it (when needing the lifecycle audit for a message) and provides clear context, but it does not explicitly name alternatives or state when-not-to-use conditions. Sibling tools like pin_history serve related but distinct purposes, yet no explicit routing is provided.

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