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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real context beyond them: the output is Markdown, it includes cited sources and an update date, and it carries a not-legal-advice caveat plus an attribution requirement. It does not say what happens for an unknown or well-formed-but-nonexistent slug, which keeps it from a 5.

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 fact (full Markdown text of one guide), then payload contents, then the legal caveat and citation rule in short declarative sentences. Nothing is padded, though the parenthetical source list (GOV.UK, HM Land Registry, the ICO, The Property Ombudsman) is slightly longer than needed to convey 'primary sources'.

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 one required parameter and no output schema, the description usefully compensates by describing the returned content (Markdown body, questions answered, sources, updated date), so an agent knows what to expect without a schema. The remaining gap is failure behavior on an invalid slug, minor for a read-only single-record fetch.

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% and the slug property already documents the pattern, length bounds, and a worked example drawn from search_guides. The description adds nothing about the slug itself, so the baseline 3 applies — the schema is doing all the parameter work.

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 ('read') and a precisely bounded resource ('the full text of one GetMovely guide'), and enumerates what the payload contains: answered questions, cited primary sources, last-updated date. The 'one guide' scoping also separates it in kind from the search_guides sibling, which returns matches rather than full text.

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?

The description never explicitly says when to call this versus search_guides; that routing is only implied by the required slug and the schema note that the slug comes from search_guides. It does give one concrete usage obligation ('cite the guide's url when you use it') and sets a scope boundary with 'General information, not legal advice', but there are no stated when-not conditions.

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