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

Annotations already signal that the operation is not read-only and not destructive. The description adds the prerequisite that the file must already be uploaded, which is useful context, but does not disclose other behavioral traits such as idempotency, error conditions, or side effects on an existing attachment.

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?

A single, non-redundant sentence that front-loads the key action and object. It adds relevant constraint ('already-uploaded') rather than repeating the title, so every word 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 low-complexity mutation with two fully documented parameters and no output schema, the description plus annotations cover the essential information needed to call the tool correctly: what is attached, to whom, and under what precondition.

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%: each parameter is documented with its role and source. The description contributes no additional parameter-level meaning, so the baseline of 3 applies.

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 ('attach'), a specific resource ('already-uploaded file'), and a target agent. This clearly distinguishes it from sibling attach_* tools (e.g., attach_vector_store, attach_mcp_server) and from detach_file.

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 phrase 'already-uploaded file' implies the file must have been uploaded before this tool is used, providing an implicit usage condition. However, the description does not explicitly state when to choose this tool over alternatives or when not to use it.

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