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

Annotations only cover readOnlyHint and openWorldHint; the description adds genuinely new behavioral context: x402 payment mechanics, the $0.003 USDC cost per successful call, that failed calls are free, the 1,000-point cap, and ISO timestamp formatting. This is meaningful disclosure beyond the annotations, though it doesn't cover rate limits or error behavior.

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 action and scoping, then layers on limits, formatting, and pricing. Reasonably tight, though the 'Information only, not financial advice' clause is boilerplate that consumes space without aiding invocation.

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, return-value explanation is unnecessary, and the description adequately covers cost, payment chain, caps, and timestamp format. It is nearly complete for a read-only price-history call, missing only guidance on interval/fidelity trade-offs and failure modes.

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 coverage is 100%, so all four parameters (tokenId, limit, fidelity, interval) are already documented in the schema, including the interval enum values and fidelity default. The description restates the interval set and the point cap but adds no syntax or edge-case detail beyond the schema, so baseline 3 applies.

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 (fetches), resource (historical price points), and scope (Polymarket outcome token), which cleanly separates it from siblings like pm_orderbook, pm_trades, or pm_resolved. It stops short of naming those alternatives, so it's clear but not sibling-differentiating.

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 implies when to reach for it (historical price series for a token) but never states when-not to use it or points to alternatives such as pm_orderbook for current depth or pm_trades for fills. Usage is inferred from the resource name rather than guided.

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