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

With no annotations, the description carries the full burden and discloses significant behavior: the message lands in the client's chat, triggers a push notification, is impersonated 'exactly as if the coach typed it', and is confirm-gated before executing. It adds tone guidance ('coach's voice, first person') but does not cover permissions/authorization or any rate-limit considerations.

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?

Four tight sentences, purpose front-loaded, followed by side effects, id source, and tone guidance. Every sentence carries unique information with no filler.

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 an un-annotated mutation tool with no output schema, the description supplies the key facts an agent needs: side effects, confirm gating, id source, and content style. It omits return/preview semantics, though the schema's confirm description partially covers that overlap.

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 only 33%, so the description must compensate, and it does: it clarifies clientId's meaning and provenance (User._id from list_clients) and constrains the text content (coach's voice, first person). Confirm-gating is echoed from the schema rather than added, keeping it just short of a 5.

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 (send) plus resource (chat message) and scope (to one of the coach's clients), immediately distinguishing it from broadcast siblings like send_organization_announcement and from send_invitation. An agent can tell exactly what this 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?

Gives clear operational context: source of the id (client's User._id from list_clients) and the confirm-gated flow. It stops short of naming when to use this versus alternatives (e.g. announcements for broadcasts), so no explicit exclusions are offered.

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