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

Annotations only carry destructiveHint=true, so the description adds real value: it discloses that each check consumes updown credits while enabled and that a read/write API key is required. It does not say what the call returns (e.g. a new check id) or note any limits on check count, which would have been the remaining useful disclosures.

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?

Four short sentences, each carrying distinct information — creation, type inference, billing impact, auth — with the API key requirement and endpoint reference trailing at the end. Zero 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?

For a 14-parameter mutation tool with no required fields and no output schema, the description covers the highest-risk unknowns (auth level, credit cost, the pulse branch). Its main omission is the return value, which matters here precisely because no output schema exists to document it.

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 14 parameters are already documented and the baseline is 3. The description nonetheless adds cross-parameter meaning the schema cannot express on its own: type is derived from the URL scheme, and the url/type pair must be used inversely for pulse checks.

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 ('Add a new monitoring check') and then clarifies the creation semantics in a way no sibling does — type inference from URL scheme, and the pulse/no-URL special case. An agent can distinguish this from updown_update_check or updown_get_check purely from the text.

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 concrete selection guidance for the tricky branch (pass type 'pulse' and omit url for cron/heartbeat checks) and surfaces the read/write API key prerequisite. It never explicitly names the alternative (updown_update_check) for modifying an existing check, so it stops short of full when/when-not routing.

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