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

Annotations already disclose readOnly, idempotent, openWorld, and non-destructive behavior. The description adds meaningful behavioral context beyond that: it is a 'paid call' with a specific cost of $0.001 USDC per call, and it is 'byte-identical to GET /chain/wallet-state' with an example URLtons. These details help an agent reason about side effects and exact output behavior without contradicting the annotations.

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 description is two well-structured sentences with the main purpose front-loaded followed by cost and chain list. The second sentence is slightly heavy due to the embedded full REST URL, but every piece of information is useful (cost, chains, and HTTP equivalence). It is appropriately sized and not verbose.

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 tool's simplicity (2 params, 1 required), rich annotations, and existence of an output schema, the description covers all necessary context: purpose, supported chains, cost, multi-chain behavior, and the exact REST-equivalent call. There are no missing pieces that would prevent an agent from invoking it correctly.

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 description does not add significant parameter semantics beyond the schema. It does show an example URL with chains and address values, which reinforces usage but is not necessary since the schema already documents them. The baseline of 3 is appropriate because the schema carries the parameter documentation burden.

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 uses a specific verb+resource: 'Balance, nonce and contract/EOA flag for one address on up to 4 chains'. It clearly identifies what is returned and the scope (one address, multiple chains), distinguishing it from single-chain sibling tools like chain_balance or chain_nonce. The phrase 'one-shot what does this wallet actually hold check' further clarifies the intent.

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 gives clear context by stating this is a 'one-shot wallet snapshot' and emphasizes the ability to check 'up to 4 chains in a single paid call', signaling when the multi-chain convenience is valuable. It does not name alternatives or provide exclusion criteria, so it is not a 5, but the usage context is explicit enough for an agent to select it appropriately.

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