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

Annotations cover the safety profile (readOnlyHint, openWorldHint), and the description adds genuinely new behavior: pending transactions report status 'pending', a fallback node is used for stale receipts, and the exact pricing/billing model ($0.002 USDC via x402, failed calls uncharged). This is substantive context beyond the annotations, though retry/rate-limit nuance could go further.

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 first sentence front-loads the complete return payload, followed by pending-state, RPC-fallback, and pricing notes in a tight sequence. Slightly dense but every sentence carries information; no filler.

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 2-param, read-only lookup with an output schema, the description is nearly complete: it covers the pending case, retrieval fallback, and payment mechanics. Output fields are described (redundant given the output schema) rather than routing guidance versus siblings, which is the main remaining gap.

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 both parameters (hash, chain) are already documented, including defaults and format. The description restates output fields rather than adding parameter meaning, 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?

The description names the specific resource (an EVM transaction) and enumerates the exact fields returned (status, block, time, sender, recipient, value, gas/fee, plus ERC-20 Transfer events). An agent immediately knows this is a single-transaction detail lookup distinct from block, address, or transfer-list tools.

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?

Usage is implied by the shape of the tool (fetch one tx by hash) but never stated against alternatives. It does not clarify when to prefer this over siblings like evm_transfers, evm_logs, btc_tx, or solana_tx, so the agent must infer chain/single-vs-list distinctions from tool names.

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