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

Annotations only declare readOnly=false, destructive=false, openWorld=true; the description adds genuinely new behavior — the update is silent (no Push Notification), the value replaces rather than increments so the call is idempotent, and 0 clears the badge. It does not cover what happens with an invalid channel slug or what the response confirms, so it stops short of a 5.

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?

Front-loads the core purpose, then alternatives, then semantics, then the optional parameter — a logical order with no filler. The only mild redundancy is 'Send 0 to clear the badge', which the schema already states, but it earns its place as a usage hint.

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?

An output schema exists, so return values need no explanation, and the description covers silence, idempotency, clearing, and the sibling alternative — everything needed to call a two-parameter mutation correctly. Minor room remains around channel-slug resolution and failure behavior.

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 100%, so both parameters are already documented, including 'Send 0 to clear it'. The description adds the important replacement-versus-increment semantics for badge, but only restates the optional channel slug targeting without explaining slug resolution or default scope beyond what the schema says.

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 ('Set the number shown on the ActivitySmith App Icon Badge') plus the target platform ('iPhone or iPad'), with concrete examples of what the number represents. It is immediately distinguishable from send_push_notification, which is named explicitly.

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?

Explicitly routes the agent: use send_push_notification 'when the user should be alerted', or that tool's badge field 'to set both at once', versus this tool for silent badge-only updates. The when-not and the alternative are both spelled out, leaving nothing to inference.

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