mailing_list_latest

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

With no annotations, the description carries full burden. It explains that it loads from EMAIL_MCP_MAILING_LISTS and allows overrides, but does not disclose whether the operation is read-only or has side effects (e.g., marking messages as read). The return shape is mentioned but not detailed.

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 description is well-structured with a title line, usage context, explicit Args section, and Returns note. It is concise, front-loaded with purpose, and every sentence adds value without redundancy.

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?

The description covers purpose, parameters, and return shape (referencing check_inbox). However, it omits error conditions, prerequisites beyond the catalog, and behavior when limit/unread_only are null. The existence of an output schema reduces the burden, but some gaps remain.

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?

Despite 0% schema coverage, the description's Args section fully explains each parameter: list_id (preset id from catalog), limit (override max messages with default), and unread_only (override UNSEEN-only). This adds significant meaning beyond the schema's type-only definitions.

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 tool's purpose: 'Fetch newest messages for a preset id', which is specific and distinct from sibling tools like check_inbox and mailing_lists_catalog. The verb 'Fetch' and resource 'newest messages' are precise.

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 provides context on typical use (newsletter drops in a dedicated IMAP folder) and references the catalog for preset ids, but does not explicitly state when not to use this tool versus alternatives like check_inbox. No exclusion criteria or alternative tools are mentioned.

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