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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds meaningful behavioral context beyond those: it states that results include venue, London-local time, price, provider, and booking link, explains the default time window (next 7 days), and discloses max_price filtering behavior (removes published above, keeps unpublished flagged slots). This fully informs the agent of what to expect.

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 concise, well-structured, and front-loads the core purpose. It first states what the tool does, then when to use it, then what filters and return values are provided. Every sentence earns its place with no fluff or repetition of schema field details.

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 tool has no output schema, the description compensates by explicitly describing the return contents and default behaviors. It covers the main filters and clarifies the London-local timezone aspect. It does not explicitly address edge cases like zero results or pagination, but mentions the limit parameter default, making it sufficiently complete for a search tool.

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 input schema already provides 100% coverage of all 9 parameters with detailed descriptions, so the baseline is 3. The tool description mentions filters generically ('Filter by sport, area/borough, date range, time of day and max price') but adds no new parameter-specific semantics beyond what the schema offers. It does not contradict 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 description clearly states 'Search bookable sports slots in London across every provider LayUp aggregates' with specific verbs and resources. It distinguishes itself from sibling tools (create_alert, get_venue, list_sports) by focusing on searching across providers, and enumerates supported sports and result contents.

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 includes an explicit 'Use when a user wants to find a court, pitch, lane, class or pickup game...' which directly tells the agent when to invoke this tool. It also lists filter criteria and result details, providing clear usage context without needing to reference alternatives.

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