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

Annotations already declare this a safe read (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description nonetheless adds meaningful context: the URL is short-lived, requires no API token, and the URL itself acts as a bearer credential, which carries real security implications for handling the output.

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?

Two tight sentences, front-loaded with the core action and ending with a security caution. Every clause earns its place with no redundancy.

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 three-parameter URL-issuing tool with safety already covered by annotations and no output schema to explain, this is largely complete. Minor gaps remain around default TTL visibility and whether the returned URL needs further handling, but nothing blocks correct invocation.

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 covers 2 of 3 parameters (key, ttlSeconds) at 67%, with bucketId left undocumented. The description adds no explicit parameter guidance, though 'short-lived' loosely hints at the TTL parameter and 'file from a bucket' maps to key/bucketId. Adequate but not compensating for the coverage gap.

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?

Specific verb (Issue), specific resource (short-lived signed URL), and specific target (file from a bucket). It clearly distinguishes itself from sibling bucket tools like file_upload, file_delete, and files_list by describing a URL-issuing read path rather than a mutation or listing operation.

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 'without an API token' implies the use case (shareable, credential-free access) and 'share with caution' adds a caution, but there is no explicit when-to-use, when-not, or named alternative. No sibling is referenced, leaving the agent to infer context from the name alone.

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