list_pending_attachments

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

With no annotations, the description carries the full burden and does so well: it discloses that returned tokens are short-lived and opaque, that source paths are never exposed, that results are oldest-first, and that identical content is collapsed with sha256/duplicate_count. It omits any statement about permissions, rate limits, or failure modes, keeping it out of 5 territory.

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?

Front-loaded with the core purpose, then behavior. Dense but every sentence adds information; the dedup/duplicate_count explanation is longer than strictly needed but earns its place by preventing a misread of duplicate results.

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?

With no output schema and no annotations, the description steps up and explains the return shape (tokens, ordering, dedup semantics), which is exactly what is needed. The remaining gap is the two parameters, which are left undocumented in both schema and description.

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%, and neither 'limit' nor 'max_age_seconds' is explained in the description. Only 'received recently' loosely hints at max_age_seconds and 'oldest first' loosely implies limit semantics; the agent gets almost no guidance on how to set these two bounded integers.

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 and resource ('List supported images ... in the server's fixed attachment inbox'), which is clearly distinct from the mutation/query siblings like get_attachment and add_attachment. It does not explicitly name a sibling to contrast with, so it falls just short of a 5.

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?

Gives an explicit trigger condition: 'Use this when the channel supplied image pixels but no usable IMAGE path.' That is a concrete when-to-use statement. It stops short of explicitly ruling out the alternative (e.g., when to use get_attachment instead), so a 4 rather than a 5.

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