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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds behavior the annotations can't: the exact row tuple returned and the requirement for a follow-up lookup to make fieldId human-readable. It doesn't mention pagination or result-size limits, which is the remaining gap.

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?

One sentence plus a short join hint; the output shape and scope are front-loaded and every clause carries information. No filler.

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?

With no output schema, the description correctly compensates by declaring the row tuple, and it flags the two-step name resolution. For a workspace-wide list it doesn't say whether results are paginated or bounded, which is the one thing an agent might still need before calling.

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% and the single parameter is documented as optional, so the baseline is met. The description goes further by spelling out the consequence of omitting projectId — you get the whole workspace — which the schema's 'optional' alone does not make explicit.

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?

States a specific verb and resource (list custom-field values) plus the exact output shape — (taskId, fieldId, value) rows — and the scope (one project or whole workspace). It also distinguishes itself from the adjacent list_custom_fields tool by positioning that one as the source of field names, so an agent can pick between them immediately.

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?

Gives clear context: use with projectId for a single project, omit it for the whole workspace, and join fieldId against list_custom_fields to resolve names. It doesn't name an explicit exclusion or a conflicting alternative (e.g. reading a single task's fields via get_task), so it stops short of a 5.

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