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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds non-obvious behavior: UK-time resolution, pagination, and crucially that a night which does not state kit is recorded in a note rather than treated as 'none' — a real query-semantics quirk not derivable from structured fields.

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 dense sentences, front-loaded with the resource and scope before the parameter nuances. Slightly telegraphic in places ('with day/frequency, signup method, backline and fee'), but every sentence carries information rather than filler.

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?

With no output schema, the description compensates by enumerating the returned fields and noting pagination. For an 8-parameter read tool with full schema coverage and read-only annotations, this is close to complete; a brief note on default/max page size handling would be the only addition.

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 100% so the baseline would be 3, but the description adds meaning beyond the schema: it explains that kit filters match 'as the listing states it' and that unstated kit is not counted as absent, and it clarifies the day parameter's natural-language inputs and UK-time resolution.

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 (search), resource (open mic nights), and scope (recurring, UK, city-level), plus the returned fields (day/frequency, signup method, backline, fee). This lets an agent distinguish it from the singular sibling get_open_mic and from search_venues/search_gigs without opening any schema.

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?

Gives concrete selection guidance for the `day` parameter ('open mic tonight / on Thursday', UK time) and for the performer-type and kit filters. It stops short of naming alternatives (e.g. get_open_mic for a single night's detail) or stating when not to use it, so it is clear context but not full routing.

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