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

Annotations already declare idempotentHint, destructiveHint=false, and openWorldHint, so the safety profile is covered. The description adds genuine value by disclosing that the call costs 0.005 USDC on eip155:84532 and that the idempotencyKey must be persisted for retries — behavior not in the annotations. It does not explain whether retries incur charges again, leaving a gap.

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 with no wasted words: purpose first, then cost, then the retry constraint. Efficient, though the brevity comes at the cost of substance rather than being purely economical.

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 paid read RPC with two params and no output schema, the description covers method, chain, cost, and idempotency, which is a reasonable minimum. It omits what the call returns and how it relates to sibling tools, so it is adequate but not complete.

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 two ordered params (block hash, index) have no descriptions, and the description never explains them — only the method name hints at their meaning. The idempotencyKey note merely repeats the schema's own detailed description. The description fails to compensate for the undocumented params.

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 largely restates the tool name ('Read eth_getRawTransactionByBlockHashAndIndex'), elaborating only with the chain id (eip155:1). It does not explain what the method actually returns (RLP-encoded raw transaction) nor differentiate it from near-identical siblings like getRawTransactionByHash or getRawTransactionByBlockNumberAndIndex. This is effectively a tautology.

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?

No guidance on when to use this tool versus the many alternative transaction-fetching siblings (by hash, by block number, non-raw variants). The cost and idempotency notes are operational, not selection criteria. An agent gets no help choosing between this and adjacent methods.

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