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

Annotations declare only readOnly/openWorld/non-idempotent; the description goes well beyond that by disclosing that every call is charged in USDC from a configured wallet, that charges are bounded by budget caps, and that results are third-party data rather than instructions (a prompt-injection warning). This is exactly the kind of operational, cost, and safety context annotations cannot carry.

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-loading is strong: the verb, the paid-call warning, and the safety note come before the catalog, and the catalog format (product, price, params, source) is scannable. Many entries are cut off mid-word with '...', which wastes space on incomplete content rather than trimming cleanly.

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?

For a multi-product router with a nested params object and no output schema, the description covers product ids, pricing, per-product parameters, and payment semantics adequately. It omits return-value shape, pagination, and error behavior, but those are secondary for a lookup tool whose main selection risk is picking the wrong product.

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 the generic 'params' object only says to look at the description, so the per-product parameter lists (q, id, code*, text) and the asterisk convention for required params are the sole source of real parameter meaning. It adds genuine value over the schema, though the truncated entries leave some params described only partially.

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 lead sentence states a specific verb and resource ('search or fetch acts by id' from 'National legislation databases and EU EUR-Lex') and the per-product list enumerates the covered jurisdictions, which distinguishes it from siblings like court_opinions or patent_lookup. The many truncated product blurbs ('by its offici...', 'with title, in-...') keep it from being fully crisp, but the core purpose is unmistakable.

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 routes the agent among its own sub-products (jurisdiction/registry per entry) and flags that calls are paid, which is implicit usage guidance. However, it never says when to use this tool versus siblings such as call_product or list_products, and it gives no exclusions or prerequisites beyond the budget note.

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