save_attachment

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

Description states the tool writes to disk and returns the file path, which matches destructiveHint false (non-destructive). It does not mention side effects beyond file writing, but that is sufficient for a non-destructive operation. No contradiction with annotations.

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?

Three concise sentences with no filler. First sentence front-loads the core purpose. Every sentence earns its place.

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 tool's simplicity (no output schema, two required params), the description fully covers purpose, usage, and prerequisite. It also references the sibling tool for alternative use cases.

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 100%, so baseline is 3. The description adds context about the env var requirement for saveTo and the use case for attachmentId, but does not significantly enhance meaning beyond the schema descriptions.

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?

Description states 'Save a single email attachment to disk by its attachmentId and return the written file path.' It clearly names the verb (save), resource (attachment), and key action (write to disk). It also distinguishes from sibling save_attachments by specifying that this tool is for single attachments with a known ID.

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?

Explicitly tells when to use: 'Use when you have a specific attachmentId from list_attachments.' It also provides an alternative: 'Prefer save_attachments to save all or filtered attachments.' No ambiguity about when to choose this tool.

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