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

With only a title annotation, the description carries the burden of behavioral disclosure. It clearly conveys a read-only operation scoped to the caller's own messages, which is useful, but it does not disclose what happens for missing ids, required authentication, or the return format.

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?

A single compact sentence with no redundant words. It front-loads the action and quickly specifies the scope and lookup key.

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 one-parameter read tool with no output schema, the description is nearly sufficient: it tells the agent exactly what to provide. It could be strengthened by noting the response shape or by explicitly contrasting with chat_sources/chat_messages, but nothing critical is missing for a basic invocation.

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 already fully documents the single parameter id as 'Stored message id' with 100% coverage. The description merely says 'by id' and adds no new format, syntax, or semantic detail 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 precise action: read one stored message, with two explicit constraints (owned by the caller, by id). It clearly identifies the resource and distinguishes itself from sibling list/write tools like chat_messages, chat_sources, and chat_send.

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 the use case: call this when you have a stored message id and want its content. However, it does not explicitly mention alternatives or when not to use it, such as listing messages or sending new ones.

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