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

Goes beyond the annotations by disclosing side-effect boundaries: it 'preserves push settings' and 'never starts a purchase,' and it requires explicit user consent. The annotations already establish idempotent, non-destructive, open-world behavior, yet the description usefully clarifies that existing channels are untouched and no billing is triggered.

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?

Three short sentences, front-loaded with the core action and consent gate before the secondary assurances. The 'new phone-linked accounts' sentence is slightly background-heavy but still earns its place by explaining when this call is needed.

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 zero-parameter mutation tool with an output schema and annotations covering the safety profile, the description supplies the remaining essentials: consent precondition, scope, and side-effect guarantees. Nothing an agent needs to invoke it correctly is missing.

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?

Zero parameters, so there is nothing for the description to disambiguate and the baseline is 4. The description correctly implies the operation is account-scoped with no configurable inputs.

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 with scope: 'Enable SMS delivery for all alerts on the connected account.' An agent can tell this configures a delivery channel rather than creating/listing/stopping alerts. It never explicitly distinguishes itself from siblings like create_alert or list_alerts, so it falls short of a 5.

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 precondition ('only after the user approves SMS notification intent') and context for when the call matters ('new phone-linked accounts have no delivery channel until configured'). It implies when-not (already-configured accounts) but names no alternative sibling tool, so no explicit routing.

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