list_messages

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description adds explicit context that it neither creates conversations nor marks messages as read, providing behavioral detail beyond the annotations. This is useful and does not contradict the annotations.

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 a single concise sentence that front-loads the primary action and side-effect caveat. Every word contributes meaning; no filler or redundant details.

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 has six optional parameters, no output schema, and no parameter descriptions, the description is too sparse. It fails to explain pagination (limit/offset), ordering (newest), filtering (read_status), or the meaning of message_type, leaving the agent with insufficient information to call the tool correctly.

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%, and the description does not compensate. It only implies the 'direction' parameter via 'recibidos o enviados' but does not explain limit, offset, newest, read_status, or message_type. With six parameters and no descriptions, the agent lacks crucial guidance on valid values and filtering semantics.

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 reads received or sent messages and explicitly notes it does not create conversations or mark messages as read. This distinguishes it from siblings like list_conversations, list_conversation_messages, and preview_message, giving a specific verb, resource, and scope.

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 context that this is a read-only operation with no side effects, which implies when it is appropriate (safe listing). However, it does not explicitly name alternatives or state when to prefer other tools like list_conversation_messages or preview_message, so it lacks direct exclusions.

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