Add a subscription

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

Annotations already declare readOnlyHint=false, idempotentHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered structurally. The description adds nothing beyond that — no note on what registering a subscription triggers externally (openWorld), whether duplicates are replaced (idempotency semantics), or any auth/scope requirements.

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 clauses, front-loaded and waste-free, which is structurally fine. The problem is under-specification rather than verbosity, so it doesn't lose points for length but gains nothing from the brevity either.

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 9-parameter mutation tool with no output schema and opaque field names, the definition is far too thin: it explains neither what gets created, nor the side effects, nor what is returned. The structured annotations partially cover the safety profile, which keeps this above the minimum.

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?

Nominal schema coverage is 100%, but every field description is filler ("Body field url (required)", "Body field hungup"), leaving domain-critical parameters like service, numbers, incoming/outgoing, and accepted unexplained. The description does nothing to compensate, so the baseline-3 allowance for high coverage is not earned here.

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?

"Add a subscription" restates the tool name and title verbatim, so the only added information is the HTTP endpoint "(PUT /subscriptions)". It never says what a subscription is in this API (webhook/event subscription?) or what adding one accomplishes, and it doesn't differentiate from placetel_list_subscriptions or placetel_delete_subscription.

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?

There is no when-to-use guidance, no prerequisites, and no mention of the sibling list/delete subscription tools. The agent must infer applicability entirely from the name and the PUT endpoint hint.

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