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

Annotations already cover the safety profile (readOnly, idempotent, non-open-world), and the description goes well beyond them with operational semantics: the ssl_days_left metric is explained plus its caveat that it 'does not show which certificate the server serves', and the page_error status is defined as the home page answering with an HTTP error so no score was stored. These are non-obvious behavioral details that materially change how results are interpreted.

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?

The core purpose is front-loaded in the first clause, and because there is no output schema, the long enumeration of returned sources and fields earns its place. The second half is one run-on sentence with heavy nested clauses, which is dense but not padded.

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 must carry the return-value burden, and it does so thoroughly for every source including pagespeed and crux. Annotations handle safety, so the only real gap is the absence of usage guidance and any note about permission or rate constraints.

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% and both parameters (days, site_id) are documented in the schema, including the default of 30 and the pointer to list_sites. The description's phrasing 'over the last N days' only loosely echoes the days parameter and adds no format or interaction detail beyond the schema, so the baseline 3 applies.

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?

The description gives a precise verb and resource ('Summarize daily metrics for a website over the last N days') and enumerates exactly which sources and metrics are covered (gsc, ga4, uptime, chatgpt_ads, google_ads, plus pagespeed and crux). That level of detail effectively distinguishes it from siblings, though no sibling is named explicitly, so it falls just short of a 5.

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?

Usage is only implied: 'over the last N days' tells an agent this is the historical daily-metrics summarizer, but there is no when-to-use/when-not-to-use guidance and no pointer to alternatives such as get_pages, get_ai_visibility or get_report. An agent must infer the right context from the enumeration of returned sources.

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