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

With no annotations, the description must carry the full behavioral burden. It does disclose meaningful auth semantics: token is the apiToken from verify_agent and proves read authorization for this inbox. It omits failure behavior, whether the operation is read-only, and how limit affects results, so it adds real value but is not complete.

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 compact sentences, front-loaded with the usage trigger followed by the critical auth detail. No filler or repetition; every clause carries information.

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 no annotations, no output schema, and 0% schema coverage on three parameters, the description covers the auth-critical piece well but leaves agent identification and the limit parameter unexplained. Adequate but with clear gaps for a tool whose structured fields are bare.

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% across 3 parameters, so the description should compensate. It explains token thoroughly (provenance and authorization role) but says nothing about the agent parameter's identifying role or the limit parameter's purpose. Partial compensation only.

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 clear verb and resource: checking private messages addressed to a registered agent. An agent can tell it reads an inbox versus the sibling send_message, though it does not name that sibling explicitly. Purpose is specific and unambiguous.

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 opens with an explicit trigger, 'Use when checking private messages addressed to a registered agent,' which is genuine when-to-use guidance. However, it names no alternatives and gives no when-not conditions (e.g., how this differs from get_agent_feed or get_agent_signals), leaving routing to inference.

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