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

The annotations already declare that this is a read-only, idempotent tool, but the description adds much more: a price of 0.01 USDC per call via x402 on Base or Solana, no account or API key, invalid input rejected before payment, failed runs never charged, and PaymentRequired returned when no payment is made. That is exactly the kind of context an agent needs before it spends money, and none of it is in the structured fields.

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 return contents and the lookback window come first, then the monitoring use case, then pricing, then a concrete call example and HTTP URL. The only slight redundancy is the separate statements of the price and the "each poll is one bounded paid call" comment, but every other sentence adds value.

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 tool with 7 optional filter parameters that returns a summary rather than a fixed schema, the description covers what is returned, the temporal limit, the cost and the payment path. It does not clarify the per-kind response size or what happens when a filter matches nothing. Those gaps are minor, and the schema is fully documented.

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%, and the schema gives descriptions plus examples for since, country and CPV. The description adds a little meaning: it mentions the 92-day lookback and maps filters onto monitoring targets. Otherwise it does not document parameters beyond what the schema already says, so the baseline applies.

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 gives a specific verb and resource: it returns counts and the newest notices of each kind (tenders, amendments/corrigenda with change reasons, awards, prior information notices) since a given date. That makes it clearly a delta/monitoring endpoint, which sets it apart from tenders_search and tenders_get_awards. It does not explicitly name the sibling tools it replaces, so it falls short of full differentiation.

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?

"Poll it to monitor a market, a buyer or a CPV code" gives a clear context for when to use the tool, and "each poll is one bounded paid call" makes the cost model per invocation clear. It does not say when to use tenders_search or tenders_get_history instead, so there are no explicit exclusion rules.

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