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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered; the description's distinctive contribution is the 'Uses 2 API calls' cost disclosure, which is real operational information an agent needs for fan-out decisions. It doesn't state whether the snapshot is cached or how fresh 'right now' is, keeping it below 5.

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 value proposition is front-loaded in the first clause, the enumeration follows, and the routing instruction plus the API-cost note close it out. No sentence is redundant with the schema or the annotations.

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 one-parameter, read-only lookup with no output schema, the description effectively stands in for the return value by listing the fields the agent will get back, and adds cost and routing context. It leaves out response shape details such as units or how the liquidation-pressure score is scaled, which would matter for interpreting the output.

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?

Only one parameter, and the schema already documents it at 100% coverage with a concrete symbol format example (BTC, ETH, HYPE, xyz:SKHX). The description adds only that the tool concerns a single market, so the schema is doing the heavy lifting — baseline 3.

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?

States a specific verb-and-resource with scope: 'everything about one market right now', then enumerates the payload (price, 24h change, liquidation-pressure score, exposure, cluster, rank, delta since previous snapshot). The 'right now' vs 'since the previous snapshot' framing implicitly separates it from coin_history, but it never names a sibling outright, so it stops short of 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?

'Start here for any question about one coin' is an explicit routing rule that tells the agent when to select this over the many aggregated siblings (market_overview, cascades, cohort_*) and 'Uses 2 API calls' gives a cost signal for multi-coin loops. No explicit when-not or named alternative is given, so a 4 rather than a 5.

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