Convert MBOX archive

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

Adds substantial context beyond annotations: hard 256 MiB and 1000-message caps, the truncated=true signal, the requirement that output_directory be supplied, one .md per message vs bundle directories, a collision-safe report, and the guarantee that the source archive is never modified. It also clarifies negative behavior (no cancellation, caps are not a time limit), which is exactly the kind of trap an agent would otherwise fall into.

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-loads the core purpose in the first sentence, then groups constraints, output behavior, and return shape into short paragraphs. Dense but every sentence carries information an agent needs; no filler or restatement of the 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?

Limits, rejection cases, side effects, and return shape are all covered, and an output schema exists so return values need no further explanation. The gap is the undocumented parameter surface: an agent can call this correctly with defaults, but cannot make informed use of the 14 optional formatting toggles.

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% across 16 parameters, so the description carries the full burden, yet it only touches output_directory (already marked required in schema) and bundles=true. Fourteen parameters — preset, dry_run, thread_mode, thread_order, include_raw_html, embed_inline_images, no_calendar_summary, and all the strip_* toggles — get no explanation of what they change or when to set them.

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 ('Convert one flat .mbox archive ... to Markdown files') with its scope ('one flat', example Gmail Takeout). The distinction from siblings is implicit but strong: convert_directory handles directories, which the description explicitly rejects, and the format (.mbox vs .eml) separates it from convert_eml.

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 explicit when-not conditions (compressed archives and Apple Mail .mbox directories are rejected) and a named alternative for out-of-scope work ('use the dead-letter CLI for larger archives'). It does not explicitly route between convert_eml/convert_directory, but the input-format constraint makes the choice unambiguous.

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