UK Data for Agents

lords_party_composition

Read-onlyIdempotent

How many members of the House of Lords each party or group has on a given date, including Crossbench peers, Bishops and non-affiliated members, from the UK Parliament Members API state of the parties. Useful for "how big is the Lords?" and Lords reform questions. Totals may differ slightly from Parliament's published figures depending on how members on leave are counted. (cost: 1 credit)

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "lords_party_composition"
  }
}

Input Schema

Name	Required	Description	Default
`date`	No	string, optional, YYYY-MM-DD, not in the future; default today (UTC)

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 5, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare read-only, idempotent, non-destructive behavior, and the description adds real value beyond them: the upstream source (UK Parliament Members API state of the parties), a data-reliability caveat about members on leave causing totals to differ from published figures, and a 1-credit cost. It does not describe the response shape, but the caveat and provenance are exactly the kind of extra context that matters here.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with the core output, then usage, then the accuracy caveat and cost. Each sentence contributes distinct information with no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-required-parameter, read-only aggregate lookup with strong annotations, the description covers scope, source, caveats, and cost. The only mild gap is that it never sketches the return shape (party-to-count mapping), which matters a bit more since there is no output schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Only one optional parameter with 100% schema description coverage (format, not-in-future constraint, UTC default), so the schema carries the semantics. The description's "on a given date" merely restates the parameter's role and adds no format or edge-case detail beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: member counts per party/group in the House of Lords on a given date, and explicitly enumerates the group categories covered (Crossbench, Bishops, non-affiliated). This clearly separates it from Commons-side siblings like commons_party_seats.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives concrete usage contexts ("how big is the Lords?", Lords reform questions), which tells an agent when to reach for it. It stops short of naming an alternative or an exclusion (e.g. Commons seat counts or lords_division_search for votes), so it is clear context without explicit routing.

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

All UK Data for Agents tools Inspect

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