get_subscribe_link

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

The description adds behavioral traits beyond annotations: 'Behavior: static local response — no API call, never rate-limited.' Annotations already declare readOnlyHint and idempotentHint, but the description provides concrete details about the tool's local nature and lack of rate limiting, which is helpful. No contradictions with annotations.

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 concise (~100 words) and well-structured: first sentence states purpose, second gives usage, third describes behavior, fourth lists returns, fifth gives agent instruction. Every sentence adds value, and the key information is front-loaded.

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?

Given the tool's simplicity (one optional parameter, no side effects, no API call), the description is complete. It explains behavior, return fields, usage scenarios, and agent limitations. An output schema exists and complements the description, but the description already provides sufficient context.

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?

The input schema has 100% coverage, describing the 'tier' parameter with an enum and description. The tool description does not add extra meaning to the parameter beyond what the schema already provides. Baseline 3 is appropriate since schema handles parameter documentation adequately.

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 tool's function: 'Get the URL where the user can subscribe to FreightUtils Pro for higher API limits.' It specifies the resource (subscription link) and differentiates from sibling tools (none are subscription-related). The verb 'get' is appropriate and the scope is well-defined.

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 explicitly says when to use: 'Use when the user asks how to upgrade or about pricing, or after any other tool errors with a 429 rate_limited body.' It also provides a clear behavioral directive: 'agents must NOT attempt to complete the subscription themselves.' This guides correct invocation and distinguishes from alternatives.

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