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

Beyond the annotations, the description discloses important behavior: missing contracts return 404, non-ERC-20 tokens return 422, both are uncharged, calls cost $0.01 with the first 25 free, failed calls are free, and repeats are not free because each call is charged. It also reinforces that the tool only reads/computes and changes nothing, consistent with readOnlyHint=true and destructiveHint=false.

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 purpose is front-loaded and the paragraph is dense but mostly purposeful. Pricing and error details are useful, though the single long block packs multiple supplemental clauses and slightly repeats the read-only and per-call-charge points.

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 simple three-parameter read-only tool with no output schema, the description covers the return shape (raw and token units, unlimited flag), error cases, and billing behavior. An agent has enough context to call it correctly and interpret common outcomes.

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%, and the schema already defines owner, spender, and token in detail. The description adds some context around token format and error behavior, but most parameter meaning is already carried by the schema, so the baseline 3 is appropriate.

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 and operation: ERC-20 token allowance on Sei, including what it returns (raw and token-unit allowance, unlimited flag). It explicitly distinguishes itself from the sibling sei_token_balance, so an agent can identify its role without opening either 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?

It gives explicit use cases — checking an approval before a swap or auditing risky open approvals — and names the alternative for a related need: 'for the owner's balance use sei_token_balance.' This is clear routing guidance with an alternative sibling called out.

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