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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds a key behavioral detail: 'Below-floor hotels return {below_bar:true} with no score exposed', which informs the caller of a special response shape. It also specifies the returned data (cosy score, evidence signals, description). This is transparent for a read-only retrieval tool, though it doesn't mention edge cases like invalid slugs.

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 description is two sentences, front-loaded with the core purpose. The first sentence states what the tool does and the second adds the critical edge-case behavior. Every sentence earns its place with no filler or repetition of schema information.

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?

Although no output schema is provided, the description explains the primary return content (cosy score, evidence signals, description) and the special below-bar case. For a tool with a single parameter and no nested objects, this is sufficient to set expectations. It could be slightly more explicit about error behavior, but overall it is contextually complete.

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?

The schema already describes the slug parameter at 100% coverage. The description enriches the semantics by explaining where the slug comes from (find_cosy_hotels results or a gotcosy.com URL), which helps the agent understand how to obtain a valid value. It also implies the slug uniquely identifies a hotel.

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 clearly states 'Get one hotel's cosy score, evidence signals and description from Got Cosy, by its slug' – a specific verb and resource. It distinguishes itself from the sibling tool find_cosy_hotels by indicating this tool is for a single hotel already identified by slug, while find_cosy_hotels presumably returns a list.

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 provides explicit context on when to use: 'by its slug (as returned in find_cosy_hotels' results, or from a gotcosy.com/en/hotels/<slug> URL)'. This explains the source of the slug and the intended workflow. It does not explicitly state when not to use it, but the context is clear and the special below-floor case adds further usage nuance.

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