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

readOnlyHint=true already tells the agent this is a safe read, so the bar for added behavior is lower. The description contributes useful payload context (each period has start, end, duration in ms), but says nothing about ordering, pagination behavior across time, or result volume limits beyond what the schema states.

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?

Two tight sentences, with the resource scoping and payload contents front-loaded before the API mapping. The trailing 'StatusCake: GET /uptime/{test_id}/periods.' is mildly redundant but cheap and useful for endpoint identification.

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 no output schema, the description correctly compensates by naming the returned fields. For a simple read-only, single-resource lookup with fully documented params, this is nearly sufficient; only paging/ordering conventions are left unstated.

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 description coverage is 100% and every parameter (after, before, limit, test_id) carries its own schema description, so the baseline of 3 applies. The description adds no parameter-level semantics such as time-window defaults or how before/after interact with paging.

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 ('the up and down periods of one uptime check') with the returned fields (start, end, duration in ms) and scopes it to a single test via the required test_id. The phrase 'The direct answer to "how long was it down?"' pins the intent, which separates it from the broader statuscake_get_uptime_history and statuscake_get_uptime_check siblings.

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 'how long was it down?' framing implies the intended usage scenario, but the description never states when to prefer this over statuscake_get_uptime_history or statuscake_get_uptime_check, and gives no exclusions or prerequisites. Usage is inferable but not directed.

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