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

With no annotations provided, the description carries the full behavioral burden. It discloses the operation is a read and adds the concrete cost ($0.003 USDC via x402), which is valuable. It does not mention response format, failure modes, or rate limits, but it does not contradict the read-only implication.

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 short sentences, with the purpose front-loaded and the cost as a secondary detail. Every word earns its place and there is 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 simple read tool with three required parameters and no output schema, the description covers the operation, network, actors, and cost. It does not specify the return format (e.g., raw uint256 vs formatted) or explicitly explain the token parameter, so it is adequate but not fully complete.

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?

The schema has 0% description coverage, so the description must compensate for the three undocumented parameters. It clarifies the roles of owner and spender, and 'ERC-20 allowance' implies token is the token address, but the token parameter is not explicitly defined and no unit/format details are provided. Partial compensation only.

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 ('Read an ERC-20 allowance'), specifies the network (Base), and names the relevant parties (owner and spender). This clearly distinguishes the tool from siblings like base_erc20_balance and base_erc20_transfers.

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 implies when to use the tool (whenever an ERC-20 allowance is needed) but provides no explicit when-not guidance or alternative routing among the many base_* sibling tools. Useful context is present, but exclusions and alternatives are absent.

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