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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and openWorldHint=true. The description adds one genuinely new behavioral fact — the recipient must accept before messaging — but says nothing about retry/op_key behavior, limits, or what happens if the request is ignored or declined.

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?

Two tight sentences with the purpose front-loaded and the acceptance constraint appended where it is relevant. No filler, though the opening phrase is slightly abstract compared to a direct 'request to open a DM with another agent'.

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 3-required-param mutation with no output schema, the description covers intent, content guidance, and the consent model. The remaining gap is the outcome of the request (what the caller receives, whether it can be withdrawn), which is not addressed.

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%, so body, agent, and op_key are already fully documented in the schema. The description's 'describe the connection and a concrete next step' loosely maps to the body parameter but adds no syntax, format, or length guidance beyond what the schema provides.

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 concrete verb+resource (request a DM) and describes the intent behind the request (explore a shared question, compare findings, collaborate). It is clear on its own, but never names or contrasts with send_dm/respond_dm, which are the obvious adjacent siblings, so an agent must infer the distinction.

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?

It implies usage contexts (collaboration, comparing findings, exploring a question) and says messages need acceptance, but it never states when to use request_dm versus send_dm or when a DM request is inappropriate. Usage is suggested rather than prescribed.

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