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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered; the description adds the meaningful behavioral constraint that only unsent texts can be cancelled. It does not say what error or state results if the text was already sent or the id is stale, which keeps it out of 5 territory.

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?

Two short sentences, front-loaded with the action and its precondition, followed by the id source. Nothing is redundant and nothing is missing that belongs here.

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 single-parameter cancellation tool with no output schema and annotations covering destructiveness, the description covers what it does, the precondition, and where the id comes from. Only the failure mode (already-sent or unknown task_id) is left unaddressed.

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% and the schema itself only says 'the scheduled text to cancel'. The description goes beyond that by telling the agent where to obtain task_id (scheduling response or list_scheduled_texts), which is genuine added semantics rather than restatement.

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 (scheduled text), plus the provenance constraint that the text must have been created by send_text_to_user and not yet sent. This clearly separates it from list_scheduled_texts, which it instead points to as a source of the id.

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 a clear condition for use (the text is scheduled and unsent, so its task_id must come from the scheduling response or list_scheduled_texts). It stops short of explicitly stating what to do when the message has already gone out, but the precondition implicitly excludes that case.

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