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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description adds important behavioral detail: delete_thread removes a whole conversation, nothing is sent, and confirmation is required first. It does not explicitly state irreversibility or permission requirements, but it meaningfully supplements the annotations.

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?

The description is a single compact sentence fragment with no wasted words, front-loading the two action names and their key semantics. The telegraphic style is efficient despite being terse.

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 destructive, multi-action tool with no output schema and 0% schema description coverage, the description covers the core action mapping but omits permanence of thread deletion, permission requirements, error behavior, and any sense of what the tool returns or confirms. It is minimally adequate but leaves meaningful gaps.

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 description coverage is 0%, so the description must carry parameter meaning. It usefully maps id to cancel_scheduled and phone/contactId to delete_thread, but it does not define expected formats, clarify the required action selector, or explain when phone versus contactId should be used.

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?

The description names both supported actions and their resources: cancel_scheduled for a queued text, delete_thread for a whole conversation. It distinguishes itself from sms_list by explaining where the id comes from, though it lacks a top-level statement of the tool's overall purpose beyond the title.

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?

It gives clear usage context: use cancel_scheduled with an id from sms_list scheduled, and use delete_thread with a phone or contactId and confirm first. It does not explicitly exclude sending or point to sms_send as an alternative, so it stops short of full when/when-not guidance.

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