UK bank holidays (gov.uk). With no year, returns the upcoming ones, soonest first, plus the next holiday. Pass a year for that year in full. (cost: 1 credit)
| Name | Required | Description | Default |
|---|---|---|---|
| year | No | YYYY | |
| division | No | england-and-wales|scotland|northern-ireland |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare this is a read-only, idempotent, open-world lookup, so the safety profile is covered. The description adds two genuinely useful traits: result ordering and the extra "next holiday" field, plus a cost of 1 credit. It does not explain region-specific behavior, which matters because bank holidays differ across the three divisions.
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 short sentences, front-loaded with the resource and source, then the no-year behavior, then the year behavior, closing with cost. Every sentence carries information; nothing is padded.
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 two-parameter lookup with no output schema, the description covers the year behavior and result ordering well, but omits the division concept entirely even though the tool spans three UK jurisdictions with differing holiday sets. It also leaves the response shape only partially described.
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 both parameters are already documented. The description adds real semantics for the optional year (no year = upcoming, soonest first, plus next holiday), which goes beyond the schema's bare "YYYY", but it says nothing about the division parameter and how region selection affects results.
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?
Description names the resource precisely ("UK bank holidays (gov.uk)") and states what the tool returns. The gov.uk attribution and UK scope distinguish it reasonably from a generic sibling like public_holidays, though the sibling is never named explicitly.
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?
It gives clear guidance on one branch point: omit year for upcoming holidays, pass a year for a full-year list. It offers no guidance versus alternatives such as public_holidays (non-UK) or working_days, which an agent has to infer from the UK scope alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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