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

Annotations only declare the generic write/non-destructive/openWorld profile; the description adds genuinely useful behavior beyond that: the scope is off by default and can only be granted by the account owner, and retries must preserve the idempotency key. It stops short of describing rate limits or exactly how the message is recorded, so not a full 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?

A single dense sentence with the core action front-loaded, followed by the idempotency and permission caveats. Nothing is redundant, though the semicolon-chained clauses are packed.

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, so the description should carry the return behavior, and it partially does by noting that human support answers the message. With auth requirements and idempotency covered, the definition is nearly complete for a simple mutation, missing only the response shape.

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 explain idempotency_key semantics. However, the 4000-character limit on message and the role of ticket_id are left entirely to the schema, so coverage is partial.

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 ('Add a message to one of the account's support tickets') and clarifies that a human answers, which distinguishes it from the automated ticket_create sibling. It does not name ticket_create explicitly, so a small amount of sibling differentiation is left implicit.

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: reuse the same idempotency_key when retrying the same message, and the required support:write scope. It doesn't enumerate alternatives (e.g., use ticket_create for a new ticket), but the scenario for calling this tool is unambiguous.

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