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

With no annotations, the description carries full burden and does disclose a major behavioral trait: this is a paid tool costing 0.01 USDC via x402 or 12 sats via Cashu/L402 Lightning, plus it previews the returned payload. It does not cover failure modes (invalid/nonexistent hash), rate limits, or default chain behavior, so it stops short of full disclosure.

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?

One dense sentence front-loads the purpose, then groups returned fields, then payment options; the long field enumeration earns its place given no output schema. Slightly list-heavy but 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 two-parameter read tool with no output schema and no annotations, the description covers what the tool does, what it returns, and its unusual payment requirement. The remaining gaps are input-side details (hash format, chain default) rather than missing decision-critical context.

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 0%, so the description must compensate. It does add meaning for 'chain' by enumerating valid values (base, ethereum, arbitrum, optimism, polygon), but says nothing about the required 'hash' parameter's format (0x-prefixed hex) or whether chain is optional and what the default is.

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 and resource ('Transaction lookup by hash on an EVM chain') and enumerates both the supported chains and the returned fields, so an agent can distinguish it from evm_balance, evm_gas, and evm_token without inspecting schemas.

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: call this when you have a transaction hash and want its details. The five valid chain values are listed, which implicitly guides the chain argument, but there is no explicit when-not guidance or routing to siblings (e.g., use evm_token for token metadata).

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