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

Annotations already cover readOnlyHint and openWorldHint, yet the description adds genuinely non-obvious behavior: pricing ($0.002 USDC per successful call via x402 on Base/Solana/Arc) and that failed calls are not charged. That is real value beyond structured fields; it stops short of explaining rate limits or result freshness.

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 source and scope, then packs search modifiers and payment terms into the remainder with little waste. It is dense — one long sentence plus a pricing sentence — but every clause carries information an agent needs.

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?

Covers source, coverage, return fields, query behavior, sort options, total count and payment model, which is sufficient for a read-only search tool. The field enumeration is somewhat redundant given an output schema exists, but nothing an agent needs to call it correctly is missing.

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%, so all five parameters are already documented; the description's mention of 'optional country' and 'newest first or best match' merely restates the schema's country and sort fields. Baseline 3 is appropriate since the schema carries the semantics.

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 ('Job vacancies from EURES, the EU job mobility portal') and pins the scope to EU/EEA public employment services, which clearly separates it from the many other generic job-board siblings (indeed, arbeitnow, dice). The enumerated returned fields further clarify the resource shape.

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?

Describes the search model ('Keyword search, optional country, newest first or best match; plus total count'), which implies usage, but never states when to prefer this over sibling job boards or when it is unsuitable (e.g. non-EU roles). No alternatives or exclusions are named.

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