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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine behavioral detail beyond that: warm-up caps of 10/20/30 a day for weeks 1-3 with 'established skips it', errors/warnings surfaced 'in plain words', whether the placement test covers the current template, and a gate verdict. It does not mention error conditions (e.g. unconfigured domain) or how stale the results may be.

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 purpose is front-loaded ('The project's sending health'), but the entire body is one long run-on sentence with a nested parenthetical list that is hard to scan. Most of the bulk is return-value enumeration, which is legitimate compensation for the missing output schema, yet it is packaged in a form that is denser than it needs to be.

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 carries the burden of describing what comes back, and it covers the major components (domain checks, warm-up, seeds, placement test, gate verdict) thoroughly. It omits how to force a fresh test or what happens when deliverability data does not yet exist, but for a single-optional-param read tool it is close to complete.

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?

There is a single optional app_id parameter at 100% schema description coverage, so the schema already explains that it comes from list_apps and defaults to the most recently added project. The description adds nothing about the parameter. Per the rubric, high coverage with no added param info lands at baseline 3.

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 states a specific verb+resource (the project's sending health) and enumerates the exact scope: SPF/DKIM/DMARC/MX/MTA-STS checks, outreach domain, warm-up caps, seed inboxes, and inbox placement results. This lets an agent distinguish it from generic siblings like get_overview or get_project_settings. It never names a sibling explicitly, so it stops short of a 5.

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?

There is no when-to-use or when-not-to-use guidance. The only contextual anchor is '(App settings, Sending)', which is a UI location, not a routing cue. Given siblings like run_inbox_test, refresh_inbox_test_results, and recheck_from_domain that mutate/refresh this same data, the absence of any 'use X to trigger a new test' guidance is a real gap.

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