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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds the geographic bound (UK parks only), consistent with openWorldHint=false, plus the slug-discovery workflow. It says nothing about result volume, pagination, or what a returned route contains.

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 short sentences, front-loaded with the purpose followed by the required input and its discovery path. No filler, no repetition of the title.

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?

For a simple two-parameter read-only listing tool with no output schema, the description covers what it does and how to supply the key input. The only real gap is the undocumented limit parameter and the absence of any hint about result size or pagination behavior.

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 50%: slug is documented in the schema, but limit (default 15, max 40) has no prose explanation anywhere. The description does add real value for slug by pointing to list_national_parks as the discovery mechanism. The limit parameter's meaning and the effect of capping results remain undocumented.

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?

"List running routes inside a UK National Park" gives a specific verb (list), resource (running routes), and a geographic scope (UK National Park) that separates it from generic siblings like search_routes. It does not explicitly say how it differs from search_routes or browse_runlists, so it stops 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?

It states the required input path clearly: pass the park slug, and use list_national_parks to discover valid slugs. That is actionable prerequisite guidance. It gives no when-not-to-use guidance or contrast with search_routes, which is the obvious alternative for route lookup.

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