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

readOnlyHint=true already tells the agent this is a safe read. The description adds a genuinely useful behavioral detail beyond the annotation: filtering happens client-side, so the full check set is always fetched. No pagination or rate-limit behavior is mentioned, keeping it below a 5.

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?

Front-loaded with the core action and returned fields, then the filtering caveat. Mostly tight, though the trailing 'updown: GET /api/checks.' is a minor API-reference fragment that does not aid tool selection.

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 compensates by enumerating the key returned fields (down, uptime, last_status, error, period, SSL, domain expiry), which is sufficient for a simple list tool. Nothing critical is missing for correct invocation.

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%, so the baseline is 3, but the description adds meaning the schema lacks: it clarifies that both filters are applied client-side rather than server-side. That is a semantic detail not present in the parameter descriptions.

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 description gives a specific verb+resource ('List all monitoring checks on the account') and enumerates the returned fields (status, period, SSL, domain expiry). It is clearly distinct from mutation siblings, but it never explicitly contrasts itself with updown_get_check or updown_find_problems, so an agent must infer the list-vs-single distinction.

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?

It notes that filtering by status or text is optional and done client-side, which implies usage, but there is no statement of when to prefer this over updown_get_check, updown_find_problems, or updown_list_downtimes. Usage is implied rather than guided.

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