mail_upload_attachment

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

With no annotations, the description should cover behavioral traits. It fails to disclose side effects, storage behavior, authentication needs, or whether the blob is temporary. Only states its purpose for email composition.

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?

The description is extremely concise: a single-purpose sentence followed by one-line parameter definitions. No redundant information.

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 has an output schema, the return value may be documented there, but the description does not explain what the uploaded blob produces (e.g., an ID) or how it integrates with email composition, leaving gaps in the full context.

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 value beyond the schema for all three parameters: 'data' is specified as Base64-encoded, 'content_type' as MIME type, and 'name' as informational only (not stored). This compensates for the 0% schema coverage.

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 action ('Upload a blob') and its specific context ('for use in email composition'), differentiating it from sibling mail tools like mail_send_email or mail_download_attachment.

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?

The description implicitly indicates the tool's role in email composition but provides no explicit guidance on when to use it over related tools like mail_import_email or mail_download_attachment, nor any conditions or prerequisites.

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