Open the existing account subscription UI. Does not create a charge.
| Name | Required | Description | Default |
|---|---|---|---|
| plan | No | Optional active plan ID or month/year | |
| token | No | Optional fallback: your agent_signup token or paired agent key, only if your MCP client can't send an Authorization: Bearer header (the header is preferred and wins). Treated exactly like the header; never shown back. |
Changes observed during successful MCP inspections.
Input schema / properties / tokenAdded value: +{
+ "description": "Optional fallback: your agent_signup token or paired agent key, only if your MCP client can't send an Authorization: Bearer header (the header is preferred and wins). Treated exactly like the header; never shown back.",
+ "maxLength": 200,
+ "minLength": 1,
+ "type": "string"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is largely covered by structured data. The description adds the useful reassurance that no charge is created, but it does not explain what the UI does next, whether a link/session is returned, or any auth implications for the optional token.
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 primary action and followed immediately by the key non-behavior. No filler, nothing redundant.
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 zero-required-param, read-only tool with no output schema and full schema coverage, the description gives an agent enough to select and invoke it correctly. Only minor context is absent (what the opened UI yields, how auth interacts with the token fallback).
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% – both 'plan' and 'token' carry detailed schema descriptions including the Authorization header preference and the note that the token is never shown back. The description adds nothing about parameters, so baseline 3 applies.
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 (opens the existing account subscription UI) and adds a scope-limiting clause ('Does not create a charge'). It is clearly distinguishable from write-ish siblings like agent_signup or forum_post, though it does not name any sibling 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?
Usage is implied: call this when the user wants to manage/subscribe to their account and you need the UI entry point. The 'does not create a charge' clause implicitly rules out using it as a payment action, but no alternative tool (e.g. get_pricing, agent_signup) is named and no when-not guidance is given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.