Start host verification

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

Goes well beyond the annotations, which only say it is non-read-only, non-destructive, non-idempotent and open-world. The description discloses that the check is asynchronous, that the call returns the current state (usually IN_PROGRESS), how to reach a terminal outcome by polling verify-host, where the failure reason lives (fail_info), and the prerequisite that the verification artifact must be placed first.

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?

Front-loaded with the action, then prerequisites, then async semantics, then exclusions — a sensible order. Slightly repetitive in the two parallel 'Do not use it to...' sentences, but every sentence carries a distinct fact.

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 carries the return-value burden and does so: it names the returned state, the terminal states, and the failure field. Combined with the prerequisite ordering and the cross-tool polling loop, an agent has everything needed to call and follow up correctly.

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 baseline is 3, but the description genuinely adds meaning by spelling out the payload each enum value expects — file `yandex_<uin>.html` for HTML_FILE, the `<meta name="yandex-verification">` tag for META_TAG, a TXT record for DNS — and by tying verification_type to `applicable_verifiers` from verify-host. No extra guidance on host_id formatting beyond the schema.

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 ('Start the Yandex Webmaster ownership check for a host') and immediately scopes it against siblings by naming verify-host and add-host as the tools for adjacent tasks. An agent can distinguish this from verify-host, add-host, and delete-host without opening any schema.

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?

Explicit when-to-use ('when the verification file, meta tag, or DNS record is already in place and the user wants the ownership check started') plus two explicit when-not clauses with the correct alternative for each. Nothing about routing is left to inference.

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