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

Annotations already declare readOnlyHint/openWorldHint, but the description adds substantial behavioral context beyond them: result ordering (clicks, highest first), cursor-based pagination, hourly-row caveats including preliminary data, and an auth requirement. This is exactly the extra context the annotations do not carry.

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 metric/resource statement, then progressively narrower details. Dense but nearly every sentence carries operational value; the definitions of CTR and average position are marginal but harmless.

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 nested objects, the description must carry return-format burden, and it does: it names the returned metrics, row ordering, pagination mechanism, and the auth requirement. An agent has everything needed to call and page through 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. The description adds meaning beyond the schema by explaining how the hour dimension behaves (24-hour view, 10-day lookback, preliminary latest hours), how CTR and average position are computed, and how cursor round-trips. It does slightly less on limit/filter/range specifics, which the schema already documents.

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 ('Returns the Performance report of a property') and enumerates the exact metrics (clicks, impressions, CTR, average position) and grouping dimensions. An agent can distinguish this from sibling reports like get_links_report or list_page_issues without opening a 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?

Gives clear context on what the tool returns and when the special hour dimension applies (last 24 hours, up to 10 days back), plus prerequisites ('Needs the user's Cotlet API key with access to this app'). It does not explicitly contrast with sibling GSC tools, so it falls short of a full when-to-use/when-not statement.

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