Get a message

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

Annotations already declare readOnlyHint and openWorldHint, so the 'Read-only' line is largely redundant, but the description goes beyond the annotations by disclosing the return payload (status, error details, status history) and the lifecycle states sent → delivered / failed, which tells the agent what meaningful states to expect.

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 front-loaded sentence with the resource, return contents, and state flow, plus a two-word safety tag. No wasted words.

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 single-resource read with no output schema, the description adequately conveys what comes back and the entity's lifecycle. It omits only edge behavior such as not-found handling and whether history is paginated or bounded.

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?

There is 1 parameter and the schema description coverage is 0%, so the description must carry the load; it only says 'by ID', which conveys that message_id is an identifier but adds no format, source, or lookup guidance beyond the schema's own regex pattern.

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?

States a specific verb (Return) and resource (one message by ID) and enumerates what the payload contains: current status, error details, and status history. The singular 'one message by ID' implicitly and clearly distinguishes it from list_messages and get_conversation_messages.

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?

Usage is only implied via the read-only nature and the ID-based lookup; there is no explicit statement of when to use this versus list_messages or get_conversation_messages, nor any mention of prerequisites or failure behavior.

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