update_custom_field_value

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

No annotations are provided, so the description carries the full burden. It does disclose an important behavioral nuance—that custom field values are stored per test case version, not just external id—which adds transparency beyond a basic write description. However, it omits other relevant behavior such as overwrite semantics, error conditions, or authentication requirements, leaving gaps.

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 two sentences, front-loads the main purpose, and includes only the critical contextual detail about versioning. Every sentence earns its place with no wasted words.

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 main purpose and the critical version/project id requirement, but it lacks information about expected outcomes or error behavior (no output schema exists). Given the tool is a write operation without annotations, the description could be more complete by mentioning success/failure signals or side effects, so it is adequate but not thorough.

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 only 25%, so the description must compensate. It adds meaning by explaining why version and projectId are needed (values belong to a specific version), and mentions the external id in the rationale. It does not, however, elaborate on the structure or constraints of the customFields array, leaving that to the schema's example.

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 the action ('Write one or more custom field values on a test case') with a specific resource and operation. It also includes the underlying API method name for additional clarity, and the verb 'write' distinguishes it from sibling read tools like get_custom_field_value.

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 explicit context on when to use this tool by stating the hard requirement for exact version and project id, explaining the per-version storage model. It does not explicitly name alternatives or exclusions, but the prerequisite guidance is clear and helpful for correct usage.

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