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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond them: it discloses that results are precomputed and refreshed every 6 hours, that the published ranking only holds the top 15, and that spend is deduplicated across sources and lifecycle stages with tenders excluded. The Greek term for direct award and the ≤1-bid definition of single_bidder also clarify metric semantics.

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-loaded with the core action, then defaults and metric definitions, then the example questions and refresh cadence. The by= parenthetical is dense and slightly overloaded, 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?

An output schema exists, yet the description still names the returned fields (afm, name, metric, total) and flags the top-15 ceiling that bounds every call. For a read-only ranking tool, nothing needed for correct invocation 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% and enums are already listed, so baseline would be 3; the description earns more by defining what each enum actually measures (COMMITTED EUR counted once, single_bidder award count, direct_award = απευθείας ανάθεση) and by explaining the hard 15 cap on limit.

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 (rank) and resource (Greek public-procurement buyers/suppliers), plus the two axes of ranking. This is clearly distinct from lookup siblings like find_entity and get_entity, which retrieve a single entity rather than a leaderboard.

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?

Example phrasings ('top 10 suppliers by public revenue', 'which buyers award most without competition') map directly onto parameter choices, and defaults are stated. It does not explicitly exclude or route away from siblings like spend_by_cpv or entity_counterparties, so it stops short of full when-not guidance.

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