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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds genuinely new context beyond that: the storage folder name, the ordering guarantee (newest first), and the shape of the returned identifiers used for attaching. It does not mention pagination or limits, which keeps it from a 5.

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?

One sentence, front-loaded with the resource and its location, then the provenance and the return payload. No filler or redundant restatement of the tool name.

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, the description usefully sketches the returned identifiers ({folder, uid, part}) and the ordering, and annotations cover the safety profile. It leaves other return fields and any result-size limits unspecified, so it is nearly but not fully complete for a one-parameter listing tool.

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 100% and the single parameter (account, described as a "list_accounts id") is fully documented in the schema. The description only restates "of an account" without adding format or sourcing detail beyond what the schema already provides, so the baseline 3 applies.

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 files waiting in the "mailmcp-uploads" folder of an account) and names the originating operations (upload_attachment or an upload link), which cleanly distinguishes it from siblings like upload_attachment and request_upload. It also states ordering (newest first) and the key fields returned.

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?

The description makes the usage context clear: this is where you look to find files that have been uploaded and are waiting, and it gives the reason to call it (to obtain the {folder, uid, part} needed to attach them). It does not explicitly name an alternative tool or state a when-not-to-use condition, so it stops short of a 5.

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