Sign private URL

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

With no annotations, the description carries full behavioral burden. It discloses security-critical traits: the signature binds to the image, prevents replay, and returns 403 if stripped. It also mentions the optional expires_in and default. No contradictions or hidden behaviors.

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, front-loading the purpose and endpoint, then providing behavioral context. Every sentence adds value with no repetition or extraneous information.

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 low complexity (2 parameters, no nested objects, no output schema), the description covers the essential information: what the tool does, security behavior, and expiration. It could mention the return format (the signed URL string) but this is not critical for 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 coverage is 100%, so the description need not add much. It does mention that expires_in is optional with a default of 3600 seconds, which the schema also specifies. The description adds no new semantic insight beyond the schema, meeting the baseline of 3.

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 verb 'mint' and the resource 'time-limited signed URL for a private image', including the HTTP endpoint. This is distinct from sibling tools (upload, list, get, delete, transform), which all handle different operations on images.

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 implies the use case (private image, time-limited access) and explains behavioral constraints (signature binding, 403 on stripping). However, it does not explicitly state when to use this tool versus alternatives, though the purpose is sufficiently clear to differentiate.

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