get_deliverability_score

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds behavioral context by specifying the return value (score, grade, factors) and that it operates at the account level, which is valuable beyond the annotations.

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 description is two sentences, front-loaded with the primary outcome, then adds a clear usage trigger. Every word earns its place with no redundancy.

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?

Given the tool's simplicity (no parameters, straightforward read-only getter) and strong annotations, the description fully covers what the agent needs: it explains what the tool returns (score, grade, factors) and when to use it. No output schema exists, but the description sufficiently describes the return values.

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?

This tool has zero parameters; the schema is empty. The description adds semantic meaning by explaining the output (score, letter grade, factors) and the account-level scope, which helps the agent understand the data returned even without parameters. A baseline of 4 is appropriate for a no-parameter tool.

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 clearly states the tool's purpose: getting the account deliverability score (0–100) and letter grade (A–F), plus the factors dragging it down. It uses a specific verb (get) and resource (deliverability score), and the 'Start here' instruction distinguishes it as the entry point for spam-related questions.

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?

The description provides explicit guidance on when to use the tool: 'Start here when asked why emails are landing in spam.' This is clear context, though it does not mention alternative tools (like run_deliverability_audit) or exclusions, so it slightly misses the top score.

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