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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered. The description goes beyond them with genuinely useful operational context: access/delay/metered usage follow the connected account, one bounded request with no server-side polling or retry, and affiliate 27 is excluded. That is real disclosure the annotations do not carry.

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?

The content is dense and mostly earns its place, but the prose is run-on and poorly punctuated ('markets Read-only Product data or price calculation'), and the key scoping fact is buried mid-sentence rather than front-loaded. Structure detracts from an otherwise short payload.

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 values need no explanation, and annotations cover the safety profile. The description adds the scoping, exclusion, and non-retry behavior an agent needs. Remaining gaps are minor for a single-resource 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?

Reported schema coverage is 0%, so the description bears more weight. It does add meaning for the path parameter ('canonical IDs' from event endpoints) and reinforces the affiliate filter ('Affiliate 27 is excluded'), but market_ids handling and the affiliate_ids=0 sentinel behavior are only in the schema text, not the description. Partial compensation merits a 3.

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?

The first clause states a specific verb and resource: get opening prices for an event's markets. It is clear what the tool returns. However, it never distinguishes itself from close siblings like v2GetEventOpeners or v1GetOpenersBySportAndDate, so the agent must infer the boundary from the name 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?

Guidance is implied rather than explicit: 'Use returned canonical IDs' hints at chaining from event endpoints, and 'never infer coverage from an empty result' warns about interpreting results. But there is no when-to-use vs when-not statement relative to the opener siblings, leaving alternative selection to inference.

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