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

With no annotations provided, the description carries the full burden. It discloses size limits, that the hub downloads the URL, and the return value (file_id). However, it omits behavioral details such as whether the operation is idempotent, any authentication requirements, error handling, or side effects beyond storage. It is not contradictory but incomplete.

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 two sentences with no fluff. The core purpose and input methods are front-loaded, followed by the return value and the alternative tool. Every clause 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 moderate complexity (5 parameters, no required ones, no output schema, no annotations), the description covers the main use case and return type but leaves gaps: the 'token' parameter is unexplained, and it does not clarify behavior when both url and content_base64 are provided, nor does it mention error conditions. Adequate for a simple tool but not fully complete.

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 80%, so most parameters are already documented in the schema. The description largely repeats that information (url vs content_base64 sizes, filename requirement, media_type guessing). It does not add meaning for the 'token' parameter, which has no schema description either. Thus, a critical parameter is entirely undocumented, lowering the score.

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 tool stores a file via two alternative inputs (URL or base64), returns a file_id for use in send_message, and explicitly differentiates from send_file. The verb 'store' plus the resource and the two methods make the purpose unambiguous and distinct from siblings.

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?

It explicitly says 'To upload and send at once, use send_file,' which gives an alternative and the condition for choosing it. This provides clear guidance on when to use this tool versus a sibling.

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