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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered, and the description reinforces it with "reads or computes only and changes nothing." It adds real context the annotations cannot express: per-call pricing ($0.01, first 25 free, failed calls free), the 404/422 failure modes for bad token contracts, and the note that repeats are charged (explaining the non-idempotent hint).

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?

Front-loaded with purpose and return shape, then usage, then token semantics, then pricing. Every clause is doing work, though the billing detail runs long and slightly crowds the operational guidance.

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?

There is no output schema, so the description carries the return-value burden and does so precisely (raw and token units plus unlimited flag). For a three-required-param read tool with full annotation coverage, an agent has everything needed to call it and interpret the result.

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 all three parameters are documented in-schema; the description restates the ticker-or-0x-contract flexibility for `token` but adds genuine value by stating what a missing contract (404) or non-ERC-20 (422) does. The `owner` and `spender` semantics are left to the schema, which fully covers them.

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 (read an ERC-20 allowance on Linea) plus the exact return shape: raw amount, token-unit amount, and an unlimited-approval flag. It explicitly distinguishes itself from the sibling linea_token_balance, so an agent can route between the two 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?

Gives two concrete use cases (pre-swap approval check, auditing risky open approvals) and names the alternative tool plus the condition that selects it ("for the owner's balance use linea_token_balance"). Nothing about when to reach for this tool is left to inference.

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