UK Legal Research MCP Server

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

The description adds valuable behavioral context beyond annotations: it specifies the data source ('official GOV.UK content API filtered to HMRC publications') and return format ('titles, URLs, summaries, and last-updated dates'). Annotations already cover safety (readOnlyHint=true, destructiveHint=false) and idempotency, but the description enriches understanding of scope and output.

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 efficiently structured in two sentences: the first states the purpose, and the second details returns and data source. Every sentence adds value with zero waste, making it easy to parse and front-loaded with essential information.

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's low complexity (single parameter), rich annotations (readOnlyHint, idempotentHint, etc.), and the presence of an output schema, the description is complete. It covers purpose, source, and return format adequately without needing to explain parameters or output details that are handled elsewhere.

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?

With 100% schema description coverage, the input schema fully documents the single 'query' parameter. The description doesn't add parameter-specific semantics beyond implying the query should be topic-based (e.g., 'VAT digital services'), which is already suggested in the schema's example. Baseline 3 is appropriate as the schema does the heavy lifting.

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 searches GOV.UK for HMRC tax guidance documents, specifying both the verb ('search') and resource ('HMRC tax guidance documents'). It distinguishes from sibling tools like 'hmrc_check_mtd_status' and 'hmrc_get_vat_rate' by focusing on document search rather than status checks or rate lookups.

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 context for when to use this tool: searching for HMRC guidance documents on GOV.UK. However, it doesn't explicitly state when not to use it or name specific alternatives among siblings (e.g., 'legislation_search' for legislation vs. guidance), though the HMRC focus provides implicit differentiation.

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