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

Annotations already declare read-only, idempotent, non-destructive, open-world, so the bar is lower; the description still adds real value: response is always an `events` array even for one ID, one bounded request with no background polling or automatic retry, access/delay/metered usage follow the account, empty results are not coverage signals, and affiliate 27 is excluded. This is well beyond what annotations convey.

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?

Purpose is front-loaded, but the body is a dense run-on of loosely related clauses, including boilerplate-ish fragments ('Read-only Product data or price calculation', 'No wagers, account changes or guarantee of returns') that dilute the high-value statements about request bounds and coverage.

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?

An output schema exists, so return-value explanation is not required; the description covers the important operational caveats (bounded request, no retry, account-dependent access, affiliate 27 exclusion, empty-result interpretation). The main missing piece is differentiation from the sibling opener tools.

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?

The schema itself carries extremely detailed descriptions for eventID, include, main_line, market_ids, hide_closed, and affiliate_ids (defaults, limits, ID meanings, sentinel behavior). The description adds almost nothing parameter-specific beyond 'Use returned canonical IDs', so the schema does the heavy lifting and 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+resource ('Get opening prices for an event') and adds scope detail — earliest recorded price per line per sportsbook. However, it never distinguishes itself from the near-identical sibling v2GetOpeningPricesByEvent or from v2GetOpenersBySportAndDate, so an agent cannot confidently choose between them from the description alone.

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?

Provides implied context ('Opening snapshots are available whenever a price has been recorded, including before, during, or after an event') and a directive to use returned canonical IDs, plus a note that empty results don't imply missing coverage. But there is no explicit when-to-use/when-not versus the sibling opener endpoints.

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