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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the safety profile is known. The description adds real value beyond that: it specifies the concrete effect ('it will not be sent') and an authorization requirement ('Editor or above') that annotations do not express.

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 compact sentence with the effect front-loaded, the lookup tool parenthesized inline, and the permission note appended. No redundant restatement of the title or 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 three-required-parameter mutation with no output schema, it covers purpose, effect, ID provenance, and authorization. Remaining gaps — whether cancellation is reversible and what is returned — are minor for this tool class, though a note on failed/already-sent cases would make it complete.

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 67% and documents project_id and conversation_id with their source tools, but scheduled_id has no schema description. The description's reference to dosai_list_scheduled_messages partially compensates by implying where the scheduled message identifier comes from, but it doesn't explicitly tie that to the scheduled_id 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 ('Cancel') and resource ('a message planned for a client') and immediately clarifies the outcome ('it will not be sent'), which distinguishes it from dosai_schedule_message and other mutation siblings. The pointer to dosai_list_scheduled_messages makes the operation unambiguous.

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?

Tells the agent where to obtain the target (dosai_list_scheduled_messages) and states the permission threshold ('Editor or above'), giving clear preconditions. It doesn't cover edge cases (already-sent messages, repeated cancellation), but the primary usage path is explicit.

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