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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: the healthScore range (0-100), its definition (share of warm-up emails landing in inbox over the last 7 full days), that it moves daily, and that it returns null when warm-up is off or before 20 emails are checked. It does not describe error behavior for invalid IDs, but the added semantics are substantive.

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?

Front-loads the purpose in the first clause, then spends the remainder on the one piece of non-obvious semantics (healthScore). Every sentence earns its place, though the healthScore explanation is dense and runs long for a single-parameter lookup.

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 compensates by explaining the most important returned field, healthScore, including its null conditions. Annotations cover the read-only profile and there is only one fully documented parameter. Only error handling and any other returned fields remain unaddressed.

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% and the single parameter is already documented as 'The numeric sender email ID (from list_sender_emails)' with a minimum bound. The description only restates 'by ID', adding nothing the schema doesn't already carry. Baseline 3 applies when the schema does all the work.

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+resource with scope: 'Retrieves a connected sending email account by ID, including its health score.' The 'by ID' qualifier implicitly separates it from list_sender_emails, though it never names that sibling. An agent can identify what it does without opening the 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?

No when-to-use guidance, no exclusions, no named alternatives. The description never mentions that list_sender_emails is the bulk counterpart, nor how this differs from get_sender_email_warmup or get_sender_reputation, which are the obvious near-neighbors for sender-account data.

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