list_custom_fields

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

No annotations are provided, so the description must disclose behavioral traits. It does state that the tool lists API-visible custom fields, provides what each entry contains, and requires an administrator API key. However, it doesn't explicitly confirm this is a read-only operation with no side effects, nor does it mention pagination or rate limits. The output schema likely covers return values, so the description adds some but not extensive behavioral context.

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 compact and front-loaded with the primary action. Each sentence contributes: main function, entry contents, usage context, and admin requirement. No fluff.

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 zero-parameter tool with an output schema, the description covers the essential context: what is listed, what each entry contains, how it is used (create_issue/update_issue), and the admin requirement. It might mention if there are any limits or ordering, but given the simplicity and output schema, it is sufficient.

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?

There are zero parameters, so there is nothing for the description to explain about input syntax. The schema coverage is trivially 100%. The description adds value by explaining the output's purpose (IDs used in create_issue/update_issue), which helps the agent understand why the tool exists even with no parameters.

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 the specific verb 'List' and identifies the resource 'custom fields visible through the API,' clearly distinguishing it from sibling list tools like list_trackers or list_statuses_and_priorities. It also states what each entry contains and why the tool is needed (for create_issue/update_issue), further clarifying its purpose.

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 that the results are needed to fill in the 'custom_fields' parameter in create_issue and update_issue, which tells the agent when to call this tool (before creating/updating issues). It also indicates a prerequisite (administrator privileges) but doesn't explicitly discuss when not to use it or alternatives, so it's clear but not exhaustive.

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