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

The description contains a critical contradiction: it claims 'Read-only and spends no quota' (consistent with readOnlyHint=true) but then describes a side effect: 'reconciles a still-'pending' row against storage and flips it to 'uploaded' the first time it sees the object.' This is a state change, contradicting the annotation. Per rubric, score 1 for contradiction.

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 dense with useful information and front-loaded with the return fields. It efficiently covers use cases, requirements, and behavior. While it is somewhat long, every sentence serves a purpose, earning a 4 rather than a perfect 5.

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?

Despite the contradiction, the description covers all needed context: it lists return fields, explains the reconciliation behavior, mentions the signed URL's validity, states quota and scope requirements, and notes what happens without a key. For a one-parameter tool with no output schema, this is very 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 100%, so baseline is 3. The description repeats the schema's hint about using the bare UUID but adds no new parameter semantics. The single parameter is well-documented in the schema; the description does not enhance it further.

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's purpose: 'Look up a stored asset by its upload id' and enumerates the specific fields returned. It distinguishes itself from sibling tools like upload_file by explaining its role in confirming out-of-band transfers, making it unambiguous.

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 explicitly states when to use the tool: confirming an out-of-band transfer landed and minting a fresh download link. It provides context by referencing upload_file's behavior and notes the required API key scope ('uploads:read'), giving clear guidance on prerequisites and use cases.

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