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

Annotations already declare this a safe, idempotent read, so the description instead spends its budget on the genuinely non-obvious behavior: a null lastCheckedAt means no check exists and the default currentStatus is NOT evidence the site is up, and null percentages mean no measurements. This is exactly the trap-avoidance context annotations cannot 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?

The core read operation is front-loaded, followed by the negative scope and then the null-value caveats, with the alternative tool named last. No sentence is filler.

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?

For a single-param read tool with full annotations and an output schema, the description covers everything needed: what it returns, that it does not trigger a live check, the null/absent-data semantics, and where to go for page-speed measurement.

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% for the single siteId parameter and its 'not a URL' warning is already in the schema, so the description adds no parameter syntax or format detail. Baseline 3 is appropriate when the schema fully documents the input.

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 and resource ('Read a saved site's latest availability check') and enumerates exactly what is returned: response time, 24h/30d uptime percentages, and ongoing incident. It is clearly distinguishable from the audit-oriented 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?

Explicitly bounds the tool ('Does not probe the site now or start monitoring') and routes the agent elsewhere for a related need ('Use audit_url or run_audit to measure page speed instead'). Both when-to-use and when-not-to-use are covered.

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