List a city’s events for a day

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

Annotations already cover readOnlyHint, openWorldHint, and idempotentHint, so the description is not burdened with restating these. It adds valuable behavioral details: date defaulting to today, the free_only filter, the invalid national hub site, and the fact that each listing includes time, price (mostly free), and venue, with URLs implied by the otc_get_post instruction. This goes well beyond the annotations and helps the agent predict output and edge cases.

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 well-structured and front-loaded with the purpose, then parameter instructions, then exclusions and alternatives. It is slightly long but every sentence serves a purpose. The final 'Read-only' is redundant given the annotation, but it's a minor redundancy. Overall, it is efficient and readable.

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 list tool with three parameters and no output schema, the description covers the essential operational details: what it returns (time, price, venue), how to filter, constraints (invalid national hub), and the path to get full write-ups (otc_get_post). It lacks explicit pagination or ordering details, but these are not critical for this tool. The description is sufficiently complete for an agent to call it correctly and interpret results.

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 input schema already documents all three parameters with descriptions. The tool description adds marginal value: it reinforces the site key requirement, mentions the date default (already in schema), and restates free_only's effect (similar to schema). It does add context about the site being from otc_list_sites, but that's more usage guidance than parameter semantics. Since the schema covers parameters, a baseline of 3 is appropriate.

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 the tool's purpose: 'List everything happening in an 'on the Cheap' city on a given date.' It names the specific verb (List) and resource (city's events for a day), and distinguishes it from siblings by focusing on a single city/day, with references to the site's events calendar. It also implicitly differentiates from otc_events_month_overview by specifying 'a given date' and from otc_search_posts by focusing on a calendar rather than a text search.

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 clear usage instructions: pass the site key, an ISO date (defaults to today), and optional free_only flag. It explicitly mentions the alternative otc_get_post for full write-ups, and warns that the national hub is not a valid site. However, it does not explicitly contrast with otc_events_month_overview, leaving the agent to infer when to use that sibling instead. This is a minor gap but the core guidance is solid.

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