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

Annotations already cover the safety profile (readOnly, not open-world, non-destructive), so the description's added value is the semantic contract: null means genuinely unpriced and never zero. That is a meaningful disclosure beyond the structured fields, though it says nothing about freshness, caching, or rate limits.

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 tight sentences, no filler, with the resource and source front-loaded and the edge-case conventions (zero address, null price) trailing where they belong.

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 no output schema, the description usefully defines the return shape (USD price keyed by address) and the null semantics. It stops short of stating ordering/coverage guarantees or how missing/null entries relate to the input list, but it is close to complete for a two-parameter read tool.

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 0%, so the description must carry parameter meaning, and it does: it defines the zero-address convention for 'addresses' and clarifies that 'block' requests a historical price. It adds real semantic content the schema lacks, only missing format details (block units, address format).

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 ('USD price per Wanchain token'), names the data source (OrbitWan's price table), and gives the keying dimension (token address), which cleanly separates it from siblings like get_token and list_tokens.

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 description explains how to use the inputs (zero address = native WAN, pass block for historical pricing) but never states when to reach for this tool versus get_token/list_tokens or what conditions would make it the wrong choice. Usage is implied rather than routed.

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