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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds meaningful context beyond annotations: the tool is free, operates at symbol-level coverage, and lists example data-source categories. This helps an agent understand expected 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?

One tightly worded sentence that front-loads the most important fact (FREE), states the output, gives concrete examples, and explains the purpose. No filler or repetition.

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 zero-parameter tool with rich annotations, this is nearly complete. It explains the return content and why an agent would use it. Without an output schema, it could add a bit more detail about the exact shape of the coverage result, but the examples and purpose are sufficient for effective invocation.

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 tool has zero parameters, so there is no parameter burden on the description. The schema coverage is effectively 100% because there is nothing to document. The description still clarifies what the no-argument call will return.

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 identifies the tool's output: which data sources cover each symbol, with concrete examples (spot on-chain DEX flow, perp venues). It is distinct from the sibling data-retrieval tools because it describes coverage metadata rather than market data itself. However, it does not explicitly name or contrast a specific sibling, so it stops short of full differentiation.

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 phrase 'FREE' and 'so you know what a paid call will return' implies the tool is a pre-flight discovery step before making paid API calls. This gives useful context but does not explicitly state when to use it versus alternatives, nor when not to use it.

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