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

Goes well past the readOnly/idempotent/openWorld annotations by disclosing the cost model (FREE, no credits), the bring-your-own-token requirement and the exact YANDEX_WEBMASTER_OAUTH_TOKEN env var, the one-token-per-account scope, and the two distinct failure payloads ({ ok:false, reason:'not_configured' } and 'no_matching_host'). It also explains what diagnostics adds over summary.siteProblems.

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 core purpose and authority-signal framing, and every sentence carries real information. It is dense and slightly over-long for a single paragraph, but there is little genuine waste.

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 and no annotation coverage of errors, the description fills the gap: it explains what is returned (indexing summary, SQI, popular queries, diagnostics), names the error shapes, and notes the missing backlinks section. An agent has what it needs to call and interpret the result.

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 both parameters are already documented in the schema; the description adds no syntax or filtering detail for queryLimit or projectId. Baseline 3 applies when the schema carries the full parameter burden.

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?

Names a specific resource (Yandex's own view of a project's domain: indexing summary, SQI, popular queries) and a specific source (Yandex Webmaster API). It explicitly distinguishes itself from the nearest sibling, stating that unlike get_bing_site_overview it has no backlinks section because Yandex publishes no backlink endpoint.

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 for when to reach for it: a third independent authority signal alongside OpenPageRank and Tranco, read from Yandex Webmaster. It also flags the free/no-credit condition and the token prerequisite, but does not state explicit exclusions beyond the backlinks contrast with get_bing_site_overview.

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