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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds a useful workflow-level behavior (pre-approval check) but does not disclose additional behavioral traits such as output shape, pagination, or chain-specific behavior beyond what annotations and schema provide.

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?

Two sentences with no filler: the first states the core purpose, the second gives immediately actionable usage guidance. Every sentence earns its place and the most important information is front-loaded.

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?

Given the strong input schema, clear annotations, and presence of an output schema, the description covers all necessary non-schema context: what is being checked, who the relevant parties are, and how the result should influence the follow-up approval action. No critical guidance 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 description coverage is 100%, so the structured schema already documents all four parameters clearly. The description adds no substantial additional parameter semantics beyond reinforcing the role of spender_address and token_addresses in the allowance context.

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 states a specific verb and resource: 'Check ERC20 token allowances for a spender address.' It clearly distinguishes this tool from related siblings by focusing on allowance checks rather than balances or approval mutations, and it explicitly ties it to write_wallet_approve.

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?

The description provides an explicit usage directive: use before write_wallet_approve and skip approving if the current allowance is sufficient. This names the relevant alternative tool and gives a concrete condition for when the read result should change the agent's behavior.

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