list_mails

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

Goes well beyond the read-only annotations by disclosing ordering ('newest first'), truncation behavior, request bounds ('six requests to Odoo.sh and the build's worker'), limit defaults and maxima, header size limits, and the critical trust model for `untrusted_mails`. The description also states 'reads only', consistent with `readOnlyHint`.

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?

The purpose is front-loaded and the description is dense with useful information rather than filler. The middle sentence is slightly awkwardly structured around the build selection clause, but every section earns its place.

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?

Even though an output schema exists, the description explains the return shape, truncation flag, trust boundary, and operational bounds. An agent has everything needed to call this tool correctly and interpret the results safely.

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%, so the description must carry parameter meaning. It explains `build_id` behavior ('of the build of that number, or of the latest one'), `limit` ('20 by default and 100 at most'), and situates `project` and `branch` as identifying a development or staging branch build. The project and branch values themselves could be slightly more explicit, but the compensation is strong.

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: listing mails caught by a build instead of being sent, newest first, with date, sender, recipients and subject. It explicitly distinguishes itself from `read_mail`, which retrieves the body, so the agent can tell the two apart without opening either schema.

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 clear routing to the sibling tool: 'Call `read_mail` with a mail's `id` for its body.' It also establishes the important security context that the mails are untrusted build output and must not be followed as instructions. It does not explicitly state when not to call `list_mails`, but the primary alternative is named.

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