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

Annotations only declare the write/idempotency profile; the description adds genuinely useful context beyond them: it returns the check id, requires an API key, and discloses the cost model (exact/contains/regex/json_schema are free, rubric/baseline invoke the LLM judge). It does not discuss scheduling floors or error behavior, which the schema partly covers.

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?

Three dense sentences, front-loaded with purpose and outcome before the cost/auth notes. No wasted phrasing, though the cost clause is somewhat redundant with the schema.

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 nested-object mutation tool with no output schema, the description covers the essential missing pieces: the return value (check id) and the auth prerequisite. Scheduling cadence and tier floors are left to the schema, but nothing critical for correct invocation is absent.

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 100%, so the schema already documents all six parameters, including the golden kinds and cost. The description restates the golden cost distinction and the meaning of baseline, adding marginal value beyond the schema's own nested descriptions.

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?

Specific verb+resource ('Add a check to one of your targets') plus a compact definition of what a check is ('runs an input... on a schedule and judges the answer with a golden'). This clearly distinguishes it from siblings like create_target, run_now, and record.

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 implies the workflow (you need a target first, per the targetId reference) and notes the API key requirement, but it never states when to prefer this over run_now or record, nor any exclusions or prerequisites beyond the auth note.

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