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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine context beyond that: the return payload is dated USD values confined to a 7-180 day window, and the grade parameter selects a raw vs graded series.

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, front-loaded with the usage trigger, followed by return shape and the exclusion. No filler, no repetition of the tool title.

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 annotations covering safety and an output schema covering the response shape, the description only needs to cover usage, prerequisites and exclusions, which it does. Minor gap: it does not clarify units/frequency of the dated values or whether the series is daily granularity, though it implies coverage of the last 7-180 days.

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 67%, and the schema already documents grade ('PSA grade... omit for raw') and card_id. The description restates the 7-180 day bound already present as min/max and the raw/PSA distinction already in the schema, so it adds little parameter-level meaning beyond the structured fields.

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 (price history) and scope: dated USD market values for the last 7-180 days, for raw or PSA-graded series. It distinguishes the tool from a simple price lookup by framing it as a trend over weeks/months, though it never names the nearest sibling (get_card_prices) as the contrasting snapshot tool.

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 a clear trigger ('when the user asks how a card's price has changed over weeks or months, or wants a trend'), a negative boundary ('Do not use for forecasts'), and a prerequisite (requires a card id from search_cards). It stops short of naming an alternative tool, so the agent must infer what to use for snapshots or forecasts.

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