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

Annotations already declare non-read-only, non-destructive, non-idempotent, closed-world. The description adds real value beyond that: the effect is scoped to 'this connection', existing data under the token is preserved, and a wrong or expired key is a no-op. It does not say whether the change is immediate or whether repeat activation is harmless, which is relevant given idempotentHint=false.

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 short sentences, front-loaded with the effect and followed by the failure guarantee and verification pointer. No filler or restated boilerplate.

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 one-parameter, no-output-schema tool with annotations covering the safety profile, this is close to complete: effect, scope, failure behavior, and a verification sibling are all covered. Only minor gaps remain (immediacy of effect, behavior when already licensed).

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% and the single param already documents the MCPL1 format, so the baseline is 3. The description earns an extra point by adding provenance the schema lacks: the key is issued at checkout and must be for this server or the bundle.

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 a specific action (turn Pro on) and its scope (for this connection), plus the exact credential shape required. It also positions the sibling license_status as the verification path, so an agent can distinguish activation from status checking without opening either 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?

It states the precondition clearly: the key must be an MCPL1.<payload>.<signature> token issued at checkout for this server or the bundle, and directs verification to license_status. It stops short of explicit when-not-to-use guidance (e.g., what to do if already Pro or if the key is for a different server).

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