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

Annotations already cover readOnly/openWorld/non-destructive, and the description adds genuinely new context: pricing ($0.01/call, first 25 free, failed calls free) and the fact that repeats are charged, which is consistent with idempotentHint=false. It omits caveats like pagination beyond the 100-log cap or rate limits, but the added billing and result-cap behavior is substantive.

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 core behavior, limits, and alternative tool are front-loaded in the first two sentences; the example and pricing follow. It is slightly dense with billing detail, but every sentence carries useful information and nothing is buried.

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 correctly states the return shape (up to 100 logs with block, transaction hash, and topics) and the scan limits. Combined with annotations and full schema coverage, an agent has everything needed to call it correctly.

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 the baseline is 3. The description clarifies that topic0 is a 0x 32-byte event signature hash and repeats the 1-1000/default-50 block range plus an address example, but these largely restate schema fields rather than adding new 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?

Names a specific resource and scope: recent contract event logs on zkSync Era via eth_getLogs, with block range, topic0 filtering, and return contents. It explicitly separates itself from zksync_receipt ('for one transaction's outcome use zksync_receipt'), so an agent can route without opening either 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?

Gives an affirmative use case ('watch transfers or contract events') and a named alternative with the condition that selects it (zksync_receipt for one transaction's outcome). Nothing material is left to inference for the main disambiguation.

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