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

Beyond the readOnlyHint annotation, the description explains that prices come from different sources, that spot and perp fields are intentionally separate, and that the difference is the basis. This prevents an agent from misreading the combined snapshot as a single unified price.

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, each carrying distinct information: scope/fields, price-source semantics, and filtering. There is no filler or duplicated annotation content.

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?

With an output schema present and readOnlyHint set, the description covers the tool's purpose, data semantics, provider merge behavior, and parameter usage. No critical calling context is missing.

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 schema already fully documents 'symbols' with an example and omit behavior at 100% coverage. The description restates that but adds no new semantic detail beyond 'covered coin'.

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 opens with a concrete noun phrase ('Per-coin market snapshot') and enumerates specific data fields, making the tool's scope clear. The per-coin scope and merged-provider wording differentiate it from market_overview and funding_current, even without naming them.

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 symbol parameter usage is explicit ('Pass symbols to filter... omit for every covered coin'), but there is no guidance about when to prefer this tool over funding_current, derivatives_open_interest, or market_candles. Usage context is implied by the snapshot wording rather than explicit.

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