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

With no annotations provided, the description fully carries the behavioral disclosure burden. It explains the exact operation (adds additional_retention_days to the current schedule or from now if expired), eligibility constraints, and includes a cost formula. This is rich, specific, and non-tautological.

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 three sentences, each contributing essential information: purpose and source, behavioral rules, and cost. It is front-loaded with the tool's primary function and contains no filler or redundant wording.

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 tool with no annotations and an output schema, the description covers all necessary guidance: what it does, which files qualify, how retention is calculated, constraints, and cost. The output schema handles return details, so no further explanation is needed.

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 schema already describes both parameters clearly, but the description adds valuable context by explaining how additional_retention_days interacts with the current schedule and the cost formula based on file size. This goes beyond the schema's simple 'days to add' and 'file name' definitions.

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 uses a specific verb and resource ('Extend retention for a file') and clearly identifies the applicable file source (files.upload_file and files.list_uploaded_files with retained_until). This distinguishes it from sibling file tools like delete, download, move, and upload.

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 states clear prerequisites: the file must have been uploaded via files.upload_file, appear in files.list_uploaded_files with retained_until, and have a completed upload session plus retention metadata. It does not explicitly name alternatives or exclusions, but the context makes the intended use case unambiguous.

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