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

Goes well beyond the annotations by disclosing the scan cap (1,000 blocks), the hard result cap (100 logs), the returned fields, and the $0.001 USDC-on-Base x402 payment per successful call — genuine cost/auth context. Note the mild tension with readOnlyHint=false, since the described behavior is a pure read; the paid call arguably justifies the conservative annotation, so this is not treated as a contradiction.

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?

Four sentences, correctly front-loaded: purpose and scope first, return shape second, usage third, cost last. Only 'Use to watch transfers or contract events' is close to filler, keeping it just short of a 5.

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?

With no output schema, the description carries the return contract (up to 100 logs with block, tx hash, topics), plus cost and filtering semantics — enough to call it correctly. Ordering of logs, empty-result behavior, and why the 1,000-block cap exists are left unstated, but these are minor for a read tool.

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%, so all three parameters (address, blocks, topic0) are already documented, including the 1-1000/default-50 range. The description restates the block cap and the meaning of topic0 but adds no syntax or format detail beyond the schema, so baseline 3 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?

States a specific verb+resource+chain: event logs emitted by a contract on Polygon PoS, with an explicit scan window and topic0 filter. The polygon_ prefix plus 'event logs' vs 'receipt'/'tx' makes it separable from the sibling chain tools without opening any schema.

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?

'Use to watch transfers or contract events' gives an implied use case but no explicit when-not and no routing to alternatives such as polygon_receipt (single-tx events) or polygon_tx. An agent must infer the boundary itself.

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