post_message

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

With no annotations, the description carries the full behavioral burden. "Persist" honestly signals a write operation, and the idempotency-key retry rule is genuinely useful behavior the schema does not convey (it warns about duplicate suppression). However, nothing is said about permissions, ordering, delivery guarantees, or failure behavior for a mutating tool.

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 short sentences with no filler, and the core action is front-loaded before the idempotency caveat. It is efficient, though for a 6-parameter mutation tool the extreme terseness borders on under-specification.

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 6 parameters, 0% schema coverage, no annotations, no output schema, and a nested metadata object, the description is far too thin to make the tool safely callable. An agent learns what the tool does and how to use the idempotency key, but not what the other five parameters mean or what the call returns.

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 description coverage is 0% across 6 parameters, so the description must compensate and largely does not. It adds meaning only for idempotency_key; room, author, message, metadata, and recipients are left entirely undefined (no formats, no constraints, no semantics for the nested metadata object or recipient list).

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?

"Persist a message" states a specific verb and resource, and it implicitly distinguishes the tool from the read-only siblings (list_messages, list_rooms, get_detail), which are all retrieval tools. It stops short of explicitly naming the sibling it contrasts with, so it is clear but not maximally differentiated.

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?

There is no when-to-use or when-not-to-use guidance, no mention of alternatives, and no stated prerequisites (e.g., must the room or recipients already exist?). The only conditional instruction ("Reuse idempotency_key only for identical retries") governs a parameter, not tool selection.

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