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

The annotations already declare readOnly, idempotent, and open-world semantics. The description adds behavioral context by mentioning the data source (European Parliament Open Data API v2) and that no auth is required, which is not covered by annotations. It also describes the output structure, but does not mention pagination or edge cases, which is acceptable for a single-profile tool.

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 four sentences: the core purpose, the output contents, a sibling-tool pointer, and source/licensing. Every sentence adds value and none are redundant. It is front-loaded with the most important information and appropriately concise.

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 that an output schema is present, the description need not detail return structures. It covers purpose, usage, output semantics, and data source, leaving no obvious gaps for an agent to call this tool correctly. The single parameter is fully documented.

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 for the single parameter mep_id, including a description and example. The tool description does not add any new parameter-related meaning beyond what the schema states, so the baseline of 3 is appropriate.

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 uses a specific verb 'Retrieve' and clearly specifies the resource: full profile and complete parliamentary membership history of a specific MEP. It also identifies the identifier type (CODICT) and explicitly differentiates from the sibling tool meps.list by stating it is for lookup. This leaves no ambiguity about what the tool does.

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 explicitly instructs to use the meps.list tool to look up MEP identifiers, implying this tool is for when the identifier is already known. It also states the tool is useful for understanding responsibilities and affiliations, giving clear context. No alternative usage is ambiguous.

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