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

With no annotations, the description must carry behavioral context, and it does disclose return fields and that no payment is required. However, it does not state whether the operation is read-only, whether auth is needed, error behavior, or rate limits. It is adequate for a simple lookup but not richly transparent.

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 concise sentences with the action and return values front-loaded. The cost note is short and useful. There is no filler or 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?

For a simple two-parameter lookup with no output schema, the description names all key return fields so an agent knows what to expect. It could mention behavior when an address is not found or unsupported, but the essentials for invoking it correctly are present.

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 schema already explains both parameters fully. The description adds no meaning beyond what 'Contract address (0x-prefixed)' and 'Blockchain network' already provide, so the baseline 3 applies.

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 action and resource: 'Look up a contract address in the Known Contract Label Registry.' It also lists the returned fields (protocol name, category, risk level, tags), making the function clear. It does not explicitly distinguish this from sibling tools, so it doesn't earn a 5.

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?

There is no guidance on when to use this tool versus alternatives, nor any exclusions or conditions. The 'Free' note addresses cost, not selection context. An agent gets no help choosing between registry_lookup and sibling tools like token_risk_metrics or contract_monitor.

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