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

With no annotations provided, the description carries the full burden. It thoroughly discloses the payment challenge (402), the need to sign and retry, the returned X-SUB-KEY token and its header usage, and the per-call pricing until subscription. This is exceptionally transparent about side effects and required steps for a mutation-like tool.

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?

The description is three sentences but each sentence carries critical information: the dual purpose, the payment flow and token, and the optional agentId. It is front-loaded with the primary action and avoids filler. For the complexity of the tool, the length is appropriate and well-organized.

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?

The description covers the activation flow, pricing, token usage, and optional linking. With no output schema, it mentions that status check returns terms but does not specify the structure of the response. This minor gap prevents a 5, but the overall context is sufficient for an agent to correctly invoke both modes.

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%, so the baseline is 3. The description adds meaningful context for the activate parameter by explaining the full flow (receive 402, sign, retry) and the token return. For agentId, it only reiterates the schema description but no additional meaning. The added flow details justify a 4.

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 clearly states the two modes of operation: checking subscription status/terms (FREE) and activating the monthly plan via the activate flag. It specifies the resource (subscription) and the verb (check/activate), and the distinct payment challenge flow sets it apart from the sibling analysis tools like evaluate_symbol and scan_bottoms.

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 when to use each mode (with or without activate:true) and hints at the cost decision (signal calls are $0.01 each until subscribing). However, it does not explicitly name alternatives or state when *not* to use this tool. The differentiation from siblings is implicit through the subscription-specific purpose, so it earns a 4 rather than a 5.

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