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

Annotations already declare readOnly/idempotent/openWorld, and the description adds genuinely non-obvious behavior: returned sample timestamps may differ from the requested instants, missing samples are silently omitted, and an empty prices array means 'not found' rather than a zero price. That last clause prevents a real misinterpretation an agent would otherwise make.

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?

Front-loaded with the core capability and packed with useful detail in a tight paragraph with no filler sentences. It does re-enumerate all eight chain ids verbatim from the schema, which is the one redundant stretch.

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 read-only, single-token lookup with an output schema present, everything an agent needs is covered: token identification, timestamp format, request limits, timestamp-fidelity caveat, and empty-result semantics. No material gap remains.

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?

With 25% schema coverage, the description must compensate: symbol vs. address+chain is disambiguated, address is clarified as a contract address on EVM versus a coin type on Sui, and the 1–100 timestamp bound is stated. The chain enum list and ISO 8601 requirement are largely repeats of what the schema already encodes, keeping it from a 5.

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 (historical USD prices for one token at 1–100 timestamps) and immediately scopes it away from wallet-bound siblings with 'without a wallet or tracked holding'. An agent can tell this apart from get_token_price and get_token_balance_history without opening either schema.

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?

Explains how to identify the token (symbol, or address + chain) and the required timestamp format, and warns to verify the returned timestamps before quoting. It gives clear context but never explicitly names an alternative sibling (e.g. get_token_price for a current quote) or states 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.