epost_download_letter

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

No annotations exist, and the description only mentions the return path format and a cryptic 'written 0600'. It does not disclose side effects, authentication needs, or error conditions, leaving the agent uninformed about important behavioral traits.

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?

Two sentences with no extraneous words. The core action is front-loaded, and the return format is specified concisely.

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?

Given the lack of annotations and output schema, the description is too minimal. It omits critical context like prerequisite steps (e.g., listing letters), error handling, and file overwrite behavior, making it insufficient for reliable agent use.

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?

The description adds minimal value beyond the schema: it explains that index and letter_id are alternatives, but does not describe the index's origin or format, and output_dir lacks any explanation. With only 33% schema coverage, the description fails to compensate adequately.

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 downloads one letter to a specified directory, with two addressing methods (index or letter_id). It distinguishes itself from sibling tools like epost_download_all and epost_get_letter.

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?

No guidance on when to use index vs letter_id, nor alternatives. No exclusionary context or when-not scenarios are provided.

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