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

Annotations already establish this as a read-only, closed-world lookup, and the description adds valuable behavioral context by naming the specific data returned (admitted/blocked verdict, gate provider, test date, workaround) and the not-found path. It does not discuss freshness guarantees or data-source limits, which would have pushed it higher.

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 definition is two sentences and front-loads the core action and return payload before the not-found fallback. The first sentence is dense with nested parentheticals, but every clause conveys distinct information.

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?

No output schema exists, and the description compensates by describing the returned fields and the miss behavior. For a simple one-parameter read-only lookup this is nearly complete, though it could say whether results include multiple test entries per service.

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 the baseline is 3, but the description goes further by giving concrete example values ('Slack', 'Polar', 'Reddit', 'Product Hunt', 'Bluesky') that clarify the expected granularity of the service parameter. The schema already notes that domains are accepted, so this is additive rather than redundant.

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 ('look up') and resource ('one service'), and enumerates exactly what the result contains: admission status, gate type, test date, and alternatives. The singular scope clearly distinguishes it from the sibling list_signup_gates.

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 phrase 'Look up one service' makes the use case clear, and the fallback behavior ('Not in the table: says so and points to the free probe skill') tells the agent what happens on a miss. It does not explicitly name list_signup_gates as the alternative for browsing all entries, so it stops short of full routing guidance.

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