Change or cancel a customer's subscription plan—free, starter, pro, team, or cancelled—by email, with approval-ready justification for risky updates.
Change a customer's plan (free, starter, pro, team) or cancel it (cancelled).
| Name | Required | Description | Default |
|---|---|---|---|
| plan | Yes | ||
| Yes | |||
| justification | No | Why you are making this call, in one sentence. The person who approves it reads this; some calls need it. |
Changes observed during successful MCP inspections.
v0.13.0Input schema / properties / justificationAdded value: +{
+ "description": "Why you are making this call, in one sentence. The person who approves it reads this; some calls need it.",
+ "type": "string"
+}v0.3.8Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden and largely drops it. 'Cancel it' is clearly destructive/possibly irreversible, yet there is no word on consequences, billing/proration effects, permission requirements, or approval behavior; only the plan-value enumeration adds anything concrete.
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?
A single front-loaded sentence with no filler, and the allowed values are packed inline rather than padded into extra sentences. It is efficient, though the extreme brevity leaves gaps that structure alone cannot fix.
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 mutation tool with zero annotations, no output schema and only 33% schema coverage, the description leaves too much unspecified: no side effects, no permission/approval semantics despite the approval-oriented 'justification' parameter, and no indication of what a successful call returns or changes.
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 low (33%) and 'plan' has no enum in the schema, so the description's value list (free, starter, pro, team, cancelled) meaningfully compensates for the most important parameter. It adds nothing about 'email' (self-evident) or how 'justification' interacts with approval beyond what the schema already 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 ('Change a customer's plan') and enumerates the allowed target values, which is more than a bare restatement. It doesn't explicitly contrast itself with any sibling, but the CRM-namespace siblings are clearly distinct operations, so disambiguation is not really at risk.
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?
The description implies usage (change or cancel a plan) but gives no when-to-use framing, prerequisites, or exclusions. It never mentions that a customer likely needs to exist first (crm_find_customer) or that the approval-gated nature of some calls matters here — usage is inferred rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.