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

Annotations already declare readOnly=true and destructive=false, and the description is consistent with them ('Reads or computes only and changes nothing'). Beyond that it discloses non-obvious behavior: an unknown hash returns 404 and is uncharged, failed calls are free, and each successful call costs $0.01 with the first 25 free — which also explains why idempotentHint is false in billing terms.

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?

Purpose, alternatives, input, error behavior, and pricing arrive in a sensible order and every sentence carries information. Slight redundancy between 'failed calls free' and 'each call is charged, so repeats are not free', and the pricing clause crowds the paragraph.

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?

No output schema exists, and the description compensates by naming the returned fields; it also covers error behavior, input format, and cost. Nothing an agent needs to invoke this correctly is missing.

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 format is already documented; the description still adds value by restating the 0x-prefixed 64-hex requirement, giving a concrete example hash, and specifying the 404 outcome for an unknown hash — the latter is meaning the schema cannot express.

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 ('Look up a Celo transaction by hash') and enumerates the fields returned (sender, recipient, value in CELO, nonce, gas limit, function selector, block), which distinguishes it from celo_receipt and celo_logs without opening any 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?

Explicitly routes the agent: 'Use to see what was sent or whether it exists; for success or failure and fees paid use celo_receipt, for emitted events celo_logs.' Both the when-to-use and the named alternatives are stated.

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