Polygon: polygonGetBalances

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 agent knows it is safe. The description adds value by detailing the return contents (native MATIC + ERC-20 tokens with address, symbol, decimals, USD value) and the caveat 'where pricing is available,' which goes beyond annotation data.

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 a single, well-structured sentence that front-loads the action and resource, then lists return details. Every word earns its place with no redundancy.

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 has no parameters, no output schema, and strong annotations, the description fully covers the tool's purpose, behavior, and return contents. The pricing caveat adds important completeness for expected output variability.

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 input schema has zero parameters, so the baseline is 4. The description clarifies that 'user's wallet' is the implicit subject, which is sufficient context. No additional parameter semantics are needed.

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 ('Return') and resource ('wallet holdings on Polygon'), including chain ID 137 and detailed return contents (native MATIC, ERC-20 token balances with contract address, symbol, decimals, USD value). This clearly distinguishes it from sibling balance tools for other chains.

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 intended context is clear: use this tool to query Polygon wallet balances. However, it does not explicitly mention when not to use it or name alternative tools (e.g., ethGetBalances), relying instead on sibling names for differentiation. This is clear context without explicit exclusions.

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