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

Annotations already cover read-only, idempotent, non-destructive, and open-world behavior. The description adds meaningful context on what the lookup reveals: the shop's name, capabilities (bookings, shop, tips, concierge), and public doors, which helps the agent reason about downstream capabilities.

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 sentences, no filler, and the usage guidance is placed at the end rather than front-loaded. Both sentences are informative, though the opening noun phrase is slightly roundabout compared to stating 'retrieves a shop by slug.'

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 one-parameter lookup with strong annotations, the description covers what the tool returns and how to obtain the slug. It does not state what happens for an unknown slug or the exact response structure, but the output is likely self-explanatory and the description is sufficient for invocation.

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 single parameter is fully documented in the schema with an example slug, so the description does not need to add much. It references 'slug' as a prerequisite for the lookup, but adds no new formatting or constraint information beyond the schema.

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 title 'Look up a shop' plus the description's explanation of the return value makes the purpose clear: given a slug, the agent learns the shop's identity, capabilities, and public doors. It does not use an explicit retrieval verb in the description, and phrases the purpose as a definition ('What a Lucerna shop is'), but it still distinguishes the resource and points to market_search for slug discovery.

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?

Explicitly says to use market_search first if the slug is not already known, which tells the agent when to reach for the sibling tool and when to use this one (when a slug is available). This is the clearest kind of routing guidance.

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