get_deliverability

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

readOnlyHint=true already establishes the safety profile, so the bar is lower, and the description still adds real context: the 30-day lookback window, the specific metrics returned, and a caution against 'fixing' deliverability by disabling tracking or stripping content. It does not mention auth scope, freshness/staleness, or caching behavior, so it stops short of 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?

Two sentences, front-loaded with the return contents; the second sentence is prescriptive rather than descriptive but is short and guards against a plausible misuse. Slightly off-purpose for a read-only getter, which keeps it out of 5 territory.

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 carries the burden of describing returns and does so (score + band, complaint rate, hard-bounce rate, guardrail status), which is the key information an agent needs. Missing only secondary details such as data freshness or how bands are defined.

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?

The tool takes zero parameters, so per the rubric the baseline is 4. The description correctly implies the tool needs no arguments and instead spends its words on what the fixed 30-day window returns.

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 ('Get the team's deliverability standing'), pins the scope to the trailing 30 days, and enumerates the headline contents (score with band, complaint/hard-bounce rates, guardrail status). This is enough to separate it from siblings like get_email_insights and get_usage without opening a schema.

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 implied by the described output, but the description never states when to call this versus get_email_insights or get_usage, and offers no exclusions or prerequisites. The remediation sentence ('Improve it by fixing per-email failures and list hygiene') is advice about acting on the result, not guidance on when to invoke the tool.

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