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

With no annotations, the description carries the full burden and does so: it declares the operation read-only, enumerates the return shape (usd, change24h as a ratio with a worked example, source), and discloses freshness metadata (asOfBlock, ageSeconds, stale). It also explains graceful degradation ('usd is null and reason says why ... instead of an error') with concrete reason codes, which is behavior no structured field here provides.

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 earning its place: purpose front-loaded, then routing rules, then return/edge-case semantics. No restatement of the name and no filler despite the density of information.

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 two-param read tool with no output schema, the description covers the return fields, the units of change24h, staleness signals, and the null/reason no-price path. Combined with 100% schema coverage and sibling routing, an agent has everything needed to call it and interpret the result.

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%, including a worked native-coin example and a full chainId legend, so the schema already does the heavy lifting. The description adds only the implicit framing of 'one whole token' as the unit (versus get_quote's amount), which is marginal beyond the structured fields. Baseline 3 is appropriate.

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+resource+scope: 'USD price of one whole token on one chain,' and qualifies the pricing source (LCX Liberty DEX indexed pools, real depth not mid-market). It explicitly distinguishes itself from siblings get_quote and search_tokens, so an agent can route without opening schemas.

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?

Gives explicit when-to-use ('use it for a token's value'), names the alternative and its selection condition ('use get_quote for what a specific amount would swap for'), and supplies a prerequisite ('search_tokens first to turn a ticker into an address'). Nothing is left to inference.

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