List configured custom fields

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

With no annotations, the description carries full weight. It discloses the schema structure (4 fixed slots, value types), the mapping concept, and how other tools consume this schema. It also explains that read tools output labels directly while write tools translate, giving the agent a comprehensive behavioral model.

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 efficiently structured: it leads with the primary purpose, then explains the schema's internal details, then provides usage guidance and sibling relationships. Every sentence adds useful information without redundancy or 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?

Given the tool's simplicity (no params) and the presence of an output schema, the description covers all necessary context: what the tool returns, why the schema exists, and how it interacts with read/write tools for custom fields. It is complete for an agent to correctly select and invoke the tool.

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?

The tool has zero parameters and the input schema is empty, so schema coverage is trivially 100%. Per the baseline rule for 0 parameters, a score of 4 is appropriate; there are no parameter semantics to add.

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 opens with 'Returns the asset custom-field schema', using a specific verb and resource. It clearly explains that custom fields are 10 fixed slots mapped to labels and value types, distinguishing this from sibling list_ tools that operate on other resource types.

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 explicitly instructs to 'Call this before reading or writing custom-field values' and differentiates when read tools already surface labels automatically versus when write tools need the schema to translate labels. This provides clear context for when to use this tool versus alternatives.

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