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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds no further behavioral context such as missing-file behavior or authentication, but it does not contradict the annotations and the operation is a straightforward read.

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?

A single, front-loaded sentence with no filler and no repetition of the schema. Every word contributes to understanding the tool's purpose.

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 one-parameter read-only getter with annotations and an output schema, this is nearly complete. The only gap is the lack of an explicit pointer to sibling tools like get_custom_fields or set_file_custom_fields for agents deciding between them.

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%, and the file_id parameter already explains its purpose. The tool description adds no new parameter semantics, placing it at the baseline.

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 names a specific action ('Get'), a precise resource ('custom field values'), and a scope ('set for a specific file'). This clearly distinguishes get_file_custom_fields from siblings like get_custom_fields and set_file_custom_fields.

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 verb and object imply this is the read-only tool for per-file custom field values, so usage is reasonably clear. However, it never explicitly says when to choose this over get_custom_fields or when to use set_file_custom_fields, so there is no direct alternative routing.

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