download_attachment

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

Discloses critical behaviors beyond annotations: writes a local file, never overwrites (numeric suffix file-1.pdf), explains the MAILWARDEN_DOWNLOAD_DIR path restriction, confirms mailbox unchanged. The 'saved' field semantics are explained. Slight gap: doesn't mention permission/error behavior for the download operation, but coverage is strong given annotations already signal non-readOnly, non-destructive, non-idempotent.

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, each earning its place: definition, directory restriction, usage trigger, side effects with concrete example, and response field meaning. Zero waste, well front-loaded with the primary action.

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?

For a non-readOnly, non-idempotent write tool with zero param documentation, the description provides strong behavioral disclosure: overwrite policy, path resolution, mailbox unaffected. An output schema exists, so return details needn't be enumerated. Minor gap: no mention of failure modes (unresolvable path, missing attachment) but solid overall.

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 coverage is 0% and there are 3 required parameters with no descriptions. The description does explain destPath semantics well (directory resolution, suffix behavior) and touches on IDs coming from get_thread. However, messageId and attachmentId meanings are only implied via the get_thread reference, not explicitly defined. Description partially compensates but doesn't fully cover all three params.

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?

Clear verb+object: 'Download an attachment to a local file path.' It distinguishes from siblings by noting IDs come from get_thread's attachment metadata, explicitly differentiating from search/read-only tools. Purpose is immediately unambiguous.

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?

Explicit 'USE WHEN' statement defines the trigger condition (user wants attachment saved to disk) and cites the exact source of input IDs (get_thread's attachment metadata). This gives strong selection guidance among the sibling tools.

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