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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: data reflects the 'latest run', `rank` is scoped to 'every ranked site', and `card` is only present 'when its report is public', with an anonymous card substituted for a site 'kept by its code' — a non-obvious privacy/availability condition.

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 purpose is front-loaded, which is good, but everything is crammed into one long run-on sentence dense with backticked field names and nested parentheticals, which makes it hard to scan. Given there is no output schema the return-value detail earns its place, but the packaging does not.

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 whole return contract, and it does: it names each field family, explains `rank` as {place, of}, sources `served` from three inputs, and conditions `card` on report visibility. An agent could call this and interpret the result without further documentation; only error/not-found behavior is unaddressed.

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?

There is a single parameter at 100% schema coverage, and the schema already says 'The site, as a domain such as example.com.' The description adds nothing about the `site` argument itself — no constraints, normalization rules, or behavior on unknown domains — so it sits at the baseline the schema earns.

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 states the resource precisely — 'one site as its latest run found it' — and enumerates its payload (score, grade, four stage grades, rank, served towns, fixes). This clearly separates it from the plural sibling mttr_sites and from report-style siblings like mttr_brief. It lacks an explicit verb ('get'/'return'), but the intent is unambiguous.

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: an agent must infer that this is the single-site drill-down used after mttr_sites or mttr_leaderboard. There is one concrete instruction — 'send it to your person with the answer' for the `card` — but no when-not-to-use guidance and no named alternative for overlapping tools such as mttr_page or mttr_brief.

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