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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds a genuinely useful disclosure that the payload 'Contains personal data', but says nothing about permissions, error behavior, or whether data is masked.

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?

Three short fragments with the core meaning front-loaded and no filler. The 'GET /messages/{messageId}' fragment is largely redundant with the parameters but minimally reinforces the path binding.

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?

There is no output schema, so field-level return expectations are unstated, and no permission or error context is given. For a trivial single-id lookup with full annotation and schema coverage this is minimally adequate but not rich.

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 100% for the single required message_id, so the schema already documents the parameter fully. 'One message by id' adds no format, source, or example beyond what the schema states.

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 ('Get') and resource ('message') scoped to a single record by id, which distinguishes it from the sibling waitwhile_list_messages. It is clear but does not explicitly name that sibling as the alternative.

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?

No when-to-use or when-not-to-use guidance is given. The single-record framing implies it is for fetching one known message rather than enumerating, but the agent must infer that this fits better than waitwhile_list_messages when it lacks an id.

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