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

Annotations already declare this is a non-readonly, non-idempotent, open-world mutation, so the safety profile is covered. The description adds real value beyond that: it warns the email is sent for real and immediately, and that the trigger must pre-exist. It doesn't mention permissions, rate limits, or delivery/return behavior, which keeps it 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?

Every sentence earns its place: purpose, use cases, prerequisite, immediate-send warning, and the do-not-use exclusion. It is front-loaded with the core action and carries no redundant restatement of the schema.

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 tool with no output schema and a nested recipient object, the description covers the operational essentials (single recipient, immediate real send, trigger prerequisite, bulk exclusion). It stops short of describing the response or error cases, a minor gap given the richness already present.

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 baseline is 3, but the description adds meaning the schema doesn't: it explains that trigger_key must already be configured and points to meisa_list_triggers, reinforcing the schema's own hint. The recipient/variables mechanics remain schema-documented.

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 ('Send a triggered (transactional) email to a single email address') and immediately scopes it via a pre-configured trigger. It distinguishes itself from the sibling meisa_send_broadcast by naming it explicitly, so an agent can route correctly without opening any 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?

Gives explicit when-to-use examples (verification code, password reset, notification), a prerequisite path (trigger_key must exist; use meisa_list_triggers), and an explicit exclusion naming the alternative (bulk → meisa_send_broadcast). Nothing is left to inference.

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