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

Annotations only give the generic safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the description's disclosure that this is 'not recorded as a real send and never goes to your contacts', plus the dependency on the active product's configured sender, is genuinely additive. It stops short of stating rate limits or how skipped addresses are reported back.

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 clause, and each subsequent sentence carries a distinct prerequisite (recipient list behavior, sender configuration, preview-only semantics). No filler or restatement of the tool name.

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?

For a two-parameter tool with no output schema and adequate annotations, the description covers the send target, the recipient eligibility constraint, the sender dependency, and the non-persistent side-effect profile. An agent has everything needed to call it correctly or route elsewhere.

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 and the schema already explains `emails` and `template_id`. The description still adds workflow meaning the schema lacks: addresses must be pre-registered via meisa_add_test_recipient, and the from-address derives from product configuration rather than a parameter.

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 ('Render a template and send it as a [TEST] email') and immediately scopes it to test recipients, which cleanly separates it from meisa_send_email and meisa_test_send_broadcast. The bracketed [TEST] marker and 'preview only' clause make the operation type unmistakable.

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?

Gives explicit operating conditions: omit `emails` to hit all saved test recipients, pass a list to target specific ones, each address must already be saved (use meisa_add_test_recipient first), and the active product must have a default sender configured. It also implies the when-not case by stating this is a preview and not a real send.

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