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

Annotations already declare idempotentHint=true, openWorldHint=true, and destructiveHint=false. The description adds genuinely new behavioral context: the call costs 0.002500 test USDC on eip155:84532, which explains the readOnlyHint=false annotation (payment is a side effect) and warns the agent a payment is required. This is useful information not available 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?

Three short, front-loaded sentences: action first, then cost, then key-retention advice. No filler, though the third sentence largely duplicates the schema's idempotencyKey description.

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 standard read RPC method with no output schema, the description covers payment and key handling but omits what the call returns (an uncle count) and how it differs from the by-number sibling. It is adequate but leaves the agent to infer return semantics and method selection.

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 50%: the idempotencyKey is fully documented in the schema, while the block-hash 'params' array has no description. The description only echoes the idempotencyKey guidance and adds nothing about the block-hash parameter, so it does not compensate for the undocumented half. Baseline 3 given partial coverage.

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 states the verb and resource but essentially restates the tool name ('Read eth_getUncleCountByBlockHash'), adding only the chain identifier (eip155:1). It does not distinguish this from the obvious sibling ethereum_eth_getUncleCountByBlockNumber, so an agent must infer the by-hash vs by-number distinction from the name alone.

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?

There is no guidance on when to use this tool versus alternatives such as ethereum_eth_getUncleCountByBlockNumber or ethereum_eth_getUncleByBlockHashAndIndex. No prerequisites or context for selection are given beyond the implicit by-hash input.

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