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

With no annotations, the description carries the full behavioral burden but discloses almost nothing beyond the basic action. It does not mention authentication, side effects, whether a conversation is created, rate limits, or what the response contains.

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?

It is a single front-loaded sentence with no bloat. The parenthetical is somewhat redundant, and the description calls the parameter 'message' while the schema calls it 'body', but the structure remains efficient.

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 messaging mutation with no annotations and no output schema, the description is too thin. It does not explain return behavior, authentication needs, conversation implications, or how this differs from reply.

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 documents listing_id as a UUID but leaves body undocumented, giving only 50% schema description coverage. The description's phrase '(requires message)' merely restates that a message/body is required and adds no format, length, or content guidance beyond the schema.

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 states a specific verb and resource: sending a message to the seller of a listing. It is clear what the tool does, but it does not explicitly distinguish itself from related siblings such as reply or read_conversation.

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 guidance on when to use this tool versus reply, list_conversations, or read_conversation. The only usage-like information is that it requires a message, which is already enforced by the schema.

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