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

Annotations only tell the agent this is a non-readonly, non-destructive, non-idempotent, closed-world action. The description adds substantial behavioral context the agent could not infer: no charge or subscription occurs, the link expires in two hours, it must be shared only with the owner, and payment actually happens in Stripe with recovery access confirmed there.

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 front-loaded with the action and each subsequent sentence earns its place by covering a distinct constraint: cost disclosure, expiry, sharing restriction, and no-charge/no-subscription. No sentence is filler.

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?

With no parameters and no output schema, the description must carry the full burden, and it does: preconditions, what the tool creates, what it does not do (charge/subscribe), link lifetime, sharing rules, and refusal handling. An agent has everything needed to call and then communicate about this tool correctly.

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 tool takes zero parameters, so there is nothing for the description to disambiguate. The baseline for zero-parameter tools applies, and the description correctly avoids inventing parameter semantics that don't exist.

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 (create) and a precise resource (a private, two-hour payment approval link for this workspace), with the subscription tier implied by the tool name. This is clearly distinguishable from siblings like threadkeep_plans (viewing plans) and threadkeep_usage (usage data) because it produces a one-time approval artifact rather than reading state.

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?

Gives a clear precondition for invocation (after discussing need and the $12/month cost with the user) and an explicit exclusion (never repeatedly prompt after a refusal). It stops short of naming an alternative sibling for the 'just show me the plans' case, so it is clear context without full alternative routing.

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