token_balances

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

No annotations exist, so the description bears full burden. It mentions optional parameters to control NFT fetching and spam filtering, and states returns include spot prices and metadata. However, it lacks details on side effects, performance impact, or pagination.

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?

Three sentences, front-loaded with purpose, no fluff. Each sentence adds distinct value: purpose, required/optional, and return type. Ideal conciseness.

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 7 parameters and no output schema, the description covers basics but lacks details on error handling, pagination, or performance considerations. Adequate but not comprehensive.

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% with each parameter described. The description adds grouping and default values for boolean parameters, but this is marginal extra value beyond the schema. 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 clearly states the tool fetches native and ERC20 tokens for an address on a specific chain, with optional NFTs. It uses a specific verb 'fetch' and resource 'tokens held by an address', distinguishing it from siblings like 'native_token_balance' or 'token_holders'.

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 required and optional parameters but offers no guidance on when to use this tool versus siblings (e.g., for current vs historical balances, single chain vs multichain). Usage is implied but not explicitly scoped.

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