Get file URL

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

With no annotations, the description carries the behavioral burden. It discloses the short-lived access token behavior for protected files and explains thumbnail syntax. It does not cover error cases or auth requirements, but the core behavior is well disclosed.

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 focused sentences with no filler. The primary purpose is front-loaded, and the special cases are explained efficiently.

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?

The description covers the tool's main purpose, thumbnail behavior, and protected-file handling. It does not mention the download parameter in prose, but the schema covers that. The return value is inferable as a URL, so its absence is not a significant gap.

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 baseline is 3. The description adds real value by giving concrete thumbnail size examples ('100x100t', '0x100') and clarifying when protected should be true (non-public file field).

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: 'Build the public URL for a file stored in a record's file field.' It clearly distinguishes this URL-building tool from sibling tools like download_file or get_file_token.

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 provides useful context for when to use thumbnail sizes and when to set protected, but it never explicitly names alternative tools or states when not to use this tool. The usage guidance is present but implied rather than contrasted with siblings.

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