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

No annotations are provided, so the description must carry the full burden. It discloses the cost per call ($0.01 via x402 payment), multilingual support, and source (CELLAR). However, it does not mention rate limits, idempotency, or any side effects. For a read-only search, the cost and return format are useful but not exhaustive.

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 contains some redundancy, notably repeating the multilingual support and legal research context. It is not overly long but could be tightened by removing duplicate phrases. The structure is adequate but not exemplary.

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 simplicity (3 parameters, no output schema), the description covers essential aspects: purpose, inputs, return fields, cost, and language options. It lacks explanation of pagination or behavior on empty results, but for a straightforward search tool, it is mostly complete.

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 description coverage is 100% (all three parameters have descriptions). The description adds context that the search is full-text title search and reinforces the language list. However, it does not provide significant additional meaning beyond what the schema already conveys, so the baseline of 3 is maintained.

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?

Description clearly identifies the resource (EUR-Lex) and action (search by keyword), specifies supported content types (EU legislation, treaties, case law, legal acts) and return fields (CELEX number, title, date). While it distinguishes from other legal tools by naming the official EU database, it does not explicitly contrast with siblings like fr_legifrance_search, so a score of 4 is appropriate.

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 states the tool is 'for legal-research, regulatory and compliance agents', providing general usage context. However, it offers no when-not-to-use guidance or explicit alternatives among siblings. The usage inference is mostly implicit from the resource name.

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