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

Goes well beyond the annotations (destructiveHint=true, readOnlyHint=false, idempotentHint=false): discloses pricing semantics (free for still-valid, charged renew for expired), the ~35-day window, insufficient-balance failure behavior, and success post-conditions (unblocked, set to auto-renew, billing_cycles_count null). This is rich operational context the agent cannot derive from structured fields.

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?

Information is front-loaded (purpose, then window, then pricing, then gating, then post-conditions) and nearly every sentence carries distinct operational facts. Slightly dense with capitalized emphasis, but no wasted sentences.

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?

With no output schema, the description compensates by stating the return value ('restored DID with its new expiration date'), the cost implications, and failure modes. Nothing an agent needs to call this 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?

Schema coverage is 100%, so the baseline is 3, but the description adds real value on confirmation_token: it explains the two-call preview-then-confirm flow and that the first call charges nothing. That explains the intent of the parameter beyond the schema's field description.

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+resource — restore a TERMINATED DID by id — and scopes it to the authenticated customer. An agent can distinguish it from siblings like list_dids, get_did, buy_did, and update_did without opening any schema.

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 explicit routing ('find terminated numbers with list_dids terminated: true'), an eligibility window (~35 days before release to public stock), and the confirmation-gated paid case ('warn the user it is a paid renew before confirming'). It names the alternative for discovery and the follow-up tool (update_did) to change auto-renew.

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