set-test-case-custom-fields

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

With no annotations, the description fully carries the transparency burden. It discloses the key behavioral detail that the update merges with existing values rather than overwriting all custom fields. However, it does not mention potential error cases, authorization requirements, or return value, which would be helpful for a complete behavioral picture.

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 extremely concise—just two sentences. The first sentence states the core purpose, and the second provides the crucial usage instruction and behavioral note. Every sentence is necessary and earns its place without any 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 has 3 required parameters, no output schema, and numerous siblings, the description adequately covers the purpose, precondition, and merge behavior. It could be improved by mentioning that the update persists immediately or what happens on invalid field IDs, but it is sufficiently complete for an experienced agent.

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 schema describes each parameter. The description adds value beyond the schema by clarifying the merge behavior and noting that the fields array uses a 'flat format' with customField.id and value id, which helps the agent understand the data structure better.

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 'Update custom field values for a test case,' specifying the verb 'Update' and the resource 'test case custom fields.' It distinguishes itself from sibling tools like 'get-test-case-custom-fields' by explicitly referencing it as a prerequisite, and from 'update-test-case' which is more general.

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 provides clear guidance on when to use the tool: after calling 'get-test-case-custom-fields' to know available fields. It explains the merge behavior, helping the agent understand that only specified fields are replaced. However, it does not explicitly state when not to use it, but the context is sufficient.

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