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

The description says the tool will 'upload it to S3,' which is a write/side-effect operation, while the annotations declare readOnlyHint=true. This directly contradicts the annotation and misrepresents the tool's mutation profile. Per the rubric, a contradiction with annotations scores 1.

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?

Very concise and front-loaded: the first sentence states the action and result, the second gives usage context, and a short returns block follows. 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?

For a simple fetch-and-upload tool with no output schema, the description supplies purpose, usage context, required IDs, and return fields. It is nearly complete, but the readOnly/upload contradiction leaves the behavioral profile ambiguous.

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 100%, so the schema already documents all three parameters, including on_behalf_of, attachment_id, and email_data_id. The description adds minor context by repeating that email_data_id and attachment_id come from search_emails results, but this adds little beyond the schema. Baseline 3 is appropriate.

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: fetching an email attachment and uploading it to S3 to return a URL. It is clear what the tool does, but it does not differentiate itself from similar siblings such as read_email_attachment or read_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?

Provides clear context: 'Use this when you need to access a file attached to an email.' It also tells the agent which IDs to supply and where they come from. However, it does not state when not to use this tool or name alternatives.

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