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

Adds substantial context beyond the annotations: it states 'Read-only' and explicitly rules out writes ('Does not create, hold, modify, or cancel a reservation'). It also clarifies the data is the same as an anonymous visitor sees, which helps the agent understand scope and potential limitations.

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?

Three sentences, front-loaded with purpose, then exclusions, then parameter requirements. Every sentence is informative and none are redundant.

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?

Given the annotations (readOnlyHint, openWorldHint) and the presence of an output schema, the description provides sufficient context: it clarifies read-only nature, what the tool does not do, and the required parameter. Nothing essential is missing for an agent to call it correctly.

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 description coverage is 100%, so the schema already documents date format and default. The description adds the note that date defaults to current date in UTC, which matches the schema but doesn't add new syntax. It also says 'Requires restaurantId', which is already in the schema's required list.

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+resource: 'Read-only bookable reservation timeslots Resy currently shows for a restaurant, date, and party size'. It distinguishes itself from siblings like resy_restaurant and resy_search by scoping exactly to availability slots for a given restaurant/date/party.

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?

Clearly implies when to use it: to check bookable timeslots. It also clarifies what it is not ('same availability an anonymous visitor sees'). However, it does not name a specific sibling alternative (e.g., resy_restaurant) or state when not to use it for non-reservation purposes.

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