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

Annotations already carry the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds useful scope ('most recent' reports) and content context plus a docs link, but says nothing about rate limits, history retention, or what happens when a monitor has no Lighthouse data.

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 sentences, front-loaded with the action and resource, with zero filler. The enumeration of report contents is slightly long given an output schema exists, and the trailing docs URL is supplementary rather than essential, keeping it just short of maximal conciseness.

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 full annotations, 100% schema coverage, and an output schema present, the description does not need to explain return values or safety. It only omits edge-case behavior (empty results, monitors without Lighthouse enabled), which is a minor gap for a simple 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?

Schema description coverage is 100% — limit, monitor_id and include_json_report are each documented in the schema, including defaults and min/max. The description adds no parameter-level detail beyond reinforcing 'most recent' reports, so the baseline 3 applies.

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 ('Get') and resource ('Google Lighthouse reports for a monitor') and enumerates the payload (performance/accessibility/best-practices/SEO scores, Core Web Vitals, flagged issues). No sibling tool covers Lighthouse, so the agent can distinguish it from the surrounding get_* retrieval tools immediately.

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?

Usage is only implied: it retrieves reports 'for a monitor', so the agent infers it needs a monitor_id of a Lighthouse-enabled monitor. There is no explicit when-to-use/when-not guidance and no stated alternatives (nothing in the sibling list overlaps, but the description doesn't say so), nor any prerequisite about the monitor having Lighthouse configured.

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