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

With no annotations, the description carries the full burden. It discloses key behaviors: non-destructive reading, inline vs. large-body handling with signed URLs limited to 3 redemptions, need to re-read for a fresh link, and pagination via next_cursor. This is rich and exceeds typical tool descriptions.

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 sentences with dense information: free, behavior, pagination. Every part earns its place and is front-loaded with the most relevant facts. No redundancy or filler.

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 read tool with no output schema and no annotations, the description explains return formats (body_b64 vs. body_url), signed-link restrictions, TTL-based retention, and pagination. It does not cover error handling or exact TTL duration, but it is adequately complete for a tool of this complexity.

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 coverage is 50%, and the description does not compensate. It only mentions 'your address' and pagination via next_cursor (which is a response field), but does not clarify limit, cursor, or filter parameters. The schema itself provides descriptions for nonce, address, and signature, leaving half the parameters unexplained in both places.

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 clearly states the function: 'Returns unacked messages for your address' — specific verb, resource, and scope. It distinguishes itself from locker_ack by mentioning that messages remain until acked, but it does not explicitly name alternatives or contrasts with sibling tools.

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?

Provides context: 'Free', 'Non-destructive', and explicitly notes that messages persist until locker_ack or TTL expiry, implying when this tool is appropriate. However, it lacks an explicit 'use this when... or use locker_ack instead' formulation, though the guidance is clear enough.

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