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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered. The description adds valuable behavioral nuance the annotations do not: cancellation is deferred until period end by default, and immediate termination requires an explicit flag. It does not mention reversibility or authorization 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?

Three short sentences, front-loaded with the default behavior the agent most needs. There is mild redundancy between 'Cancels one subscription' and the first sentence, but nothing is padded or buried.

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 destructive mutation with no output schema, the description covers the key behavioral decision (deferred vs immediate cancellation) and annotations cover safety. Missing only edge-case handling (e.g., already-cancelled subscriptions) and auth/business-scope guidance.

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 all three parameters are documented in the schema. The description reinforces the `now` semantics (immediate vs period end) but adds nothing about the `business` acting-on-behalf parameter. Baseline 3 is appropriate when the schema carries the load.

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 ('Cancel a subscription') and clarifies cardinality ('Cancels one subscription'). It does not differentiate itself from siblings like agenta_subscriptions_change_plan, but the core purpose is unambiguous.

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 explains the default cancellation mode (period end) and how to override it ('set immediately to end it now'), which is implied usage guidance. However, it never states prerequisites, when cancellation is appropriate versus change_plan, or what happens if no active subscription exists.

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