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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, and the description does add real context: the registry is self-declared and unverified, ministers' interests are excluded, and the call costs 1 credit. It stops short of describing pagination, result volume, or what an empty or null response means, which matters for an openWorld data feed.

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?

Front-loads the core purpose with the category list, then tacks on audience, caveat and cost in short trailing sentences. The opening sentence is dense with enumerated categories but every clause carries information; nothing is 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?

For a single-parameter read tool with no output schema, the description covers what is returned (payment details and registration dates) and the key caveat (unverified declarations, ministers excluded) plus the credit cost. The remaining omission is response shape/pagination, which is a minor gap given the low complexity.

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% and there is only one parameter, whose schema description already explains the integer member id and where to obtain it (mp_lookup or constituency_search). The description contributes nothing about memberId, so this sits at the baseline where the schema does all the work.

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+resource (declared financial interests of an MP or peer) and enumerates the categories covered (outside jobs and earnings, donations, gifts and hospitality, overseas visits, shareholdings). It also names the source system (UK Parliament Members API), which cleanly separates it from siblings like member_career_history or mp_contact_details.

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 use-case framing — answering 'who pays or funds my MP?' for constituents, journalists and due diligence — which tells an agent exactly what question this tool serves. It also carves out an exclusion (Cabinet Office-published ministers' interests are not included), though it never points the agent at an alternative sibling for those or for member resolution.

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