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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: no API key is required, sign-up collects a work email and a 6-digit code sent by Whimbrel, and the app is handed a token with nothing to paste. It does not describe the returned shape when plan is omitted, but otherwise the agent knows what to expect from the interaction.

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 purpose and plan semantics are front-loaded and efficient, and the 'no key is required' and team-of-5 escalation lines earn their place. The closing sentence walking through the rep entering a work email, a 6-digit code, and token handoff is end-user narration that is tangential to selecting and invoking the tool, and it dilutes an otherwise tight definition.

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 one-parameter, read-only tool with no output schema, the description covers what is returned (a sign-up link), how billing differs per plan, the omit-for-both behavior, the no-key requirement, and the team escalation path. The only real gap is that it never states the response format or whether omitting plan returns two links versus one object, but that is minor given the tool's simplicity.

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% and the single enum parameter is already documented, so baseline is 3. The description earns above baseline by explaining the meaning behind each enum value: individual is billed monthly, individual_year is billed once a year at a lower monthly rate, and omitting returns both.

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 first sentence states a specific verb and resource: it returns the sign-up link for Whimbrel's single plan, along with the free-month framing. That is far clearer than the vague name 'get_access' and is unmistakably distinct from data-oriented siblings such as company, people, or deep_record. It stops short of an explicit 'use this when the user asks about pricing or sign-up' routing statement, but the purpose itself 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?

The description gives concrete invocation guidance: pass plan as individual or individual_year, or omit it for both, plus an explicit exclusion routing teams of 5+ to a contact URL. What it lacks is a stated trigger condition (e.g. 'call this when the user asks how to sign up or what it costs'), which is left implicit.

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