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

Goes well beyond the annotations (which only say it is not read-only and not destructive) by disclosing blast radius: every invitation path — inviteTesters, inviteApplicants, publish fan-out, and dashboard sends — switches to this template when active. It also warns that mail is sent from a no-reply address so reply-based CTAs fail, and notes the draft is preserved on deactivation.

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?

Purpose is front-loaded in the first sentence and the remaining sentences are ordered from effect to validation to caveats. It is dense and em-dash-heavy, and a few clauses (e.g. the explanation of why subject placeholders are rejected) could be trimmed, but almost every sentence carries operational information.

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?

No output schema exists, yet the description covers side effects, validation constraints, mode behavior, and where to read the current state. For a mutation tool with a 4-parameter schema, nothing an agent needs to call it correctly is missing.

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%, so the baseline is 3, but the description adds real meaning: the exact whitelist of allowed template variables, the rendered-text character cap for the message, the rule that subjects support no variables at all, and the cross-field activation requirement. Partial-update semantics ("provide only the fields to change") are also stated beyond the schema's field-level notes.

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?

Opens with a specific verb and resource: "Configure this beta project's custom tester invitation email." The scope (per-beta-project template for invitation emails) is unambiguous and clearly distinct from the read-side sibling getProductOverview, which the description names for reading the current value.

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?

Explicitly states the two modes (activated vs not activated and what happens to the stored draft in each), that only fields to change need to be provided, that activation requires both subject and message, and that configuring sends nothing by itself. It also names getProductOverview as the way to inspect the current template. When-to-use and how-to-use are both covered.

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