check_service_status

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

With no annotations provided, the description carries the full burden of visibility. It discloses that the endpoint is public and works without an API key, implicitly signaling no authentication requirement and a read-only (non-mutating) nature via 'check'. It does not mention rate limits or response specifics, but for a simple health-check tool with an output schema, the disclosed behavior is sufficient.

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 a tight two-sentence structure. The first sentence states what the tool does, and the second gives usage context and an example. There is zero filler; every word earns its place.

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 zero-parameter signature, a straightforward read-only purpose, and the presence of an output schema, the description covers everything an agent needs to call it correctly. The example clarifies the diagnostic intent, and no further context is necessary.

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 tool has zero parameters, so there is nothing to explain. The baseline for zero parameters is 4, and the description adds no parameter-related ambiguity.

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 states a clear verb ('Check') and a specific resource ('live health of upstream government services'), and enumerates the exact services (VIES, EORI, HMRC, GLEIF). This unambiguously distinguishes the tool from its sibling validation and lookup tools (e.g., validate_vat, lookup_company_by_vat), which all perform different operations.

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 tells the agent when to use it: 'Use it to explain why a validation returned reduced confidence' and gives a concrete example (Germany's VIES endpoint down). It also notes that it is a public endpoint requiring no API key. However, it does not explicitly state when not to use it or name alternative tools, so it misses the full 'when/when-not/alternatives' bar for a 5.

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