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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the description only needs to add scope. It does: only permit-requiring trails reservable on madeira.fun are returned, and the exact fields (seo_slug, code, name, island, status, links) are disclosed. Without an output schema, ordering and pagination remain unstated, which keeps it at 4.

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?

Two tight sentences with the resource and scope front-loaded, the return contract second, and the optional filter last. No filler and nothing repeated from the schema or annotations.

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 parameter, no output schema, and full annotation coverage, the description supplies everything needed: what is listed, what comes back, and how filtering behaves. Only the absence of any ordering or result-size guidance prevents a 5.

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 single optional parameter is already documented, so the baseline is 3. The description adds genuinely new semantics: the query matches against code or name and 'accents ignored', which is not in the schema and materially affects how an agent should phrase a name filter.

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?

Specific verb (List) plus a precisely scoped resource: Madeira trails requiring a government permit, that have a set start time, and that are reservable on madeira.fun. It also enumerates the returned fields including seo_slug, which makes it clearly the discovery/entry-point tool relative to the booking-oriented siblings.

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 parenthetical 'use it in the other tools' tells the agent this is the first step and how its output feeds siblings like check_trail_availability and start_reservation. It stops short of explicitly naming which sibling to call next or ruling out cases, so it falls just below a full 5.

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