mail_download_raw

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), yet the description adds substantive behavior: output is written to a private local file, returns path/byte count/SHA-256, and results over 64 KiB are spilled to a private JSON file with a compact summary plus completeResultFile. These operational details go well beyond what annotations provide.

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?

Four tight sentences, front-loaded with the primary action before the return/truncation details. Every sentence carries information, though the two return-behavior sentences could be merged without loss.

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 correctly documents the return values (file path, byte count, SHA-256) and the truncation/completeResultFile escape hatch, making it self-sufficient on the output side. Its one gap is the complete absence of parameter guidance for a four-required-param 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 description coverage is 0% across four required parameters (accountId, folder, uid, uidValidity), so the description carries the full burden — but it mentions none of them. It adds no meaning about identifier formats, the uidValidity pairing, or why folder plus accountId are needed, leaving the agent to infer everything from bare property names.

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 ('Stream the complete original RFC822 message (.eml) ... into a private local file') and explicitly differentiates from read-into-output siblings by noting it does not load the message into tool output. An agent can distinguish this from mail_get_message and mail_download_attachment without opening any 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?

Conveys the scenario clearly through the phrase 'byte-preserving source of truth' and the contrast with loading into tool output, implying when raw archival retrieval is wanted. It stops short of naming an alternative tool or stating explicit exclusions, so it earns a 4 rather than a 5.

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