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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description adds the crucial behavioral detail that this does not flip a plan switch but mints a hosted checkout URL the user must open and pay through. It leaves open whether repeated calls create duplicate links or what happens on an already-maxed plan.

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?

Three short sentences: action, return value, trigger — in that order. Every sentence carries information and nothing is padded.

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 output schema, the description covers the missing return-value contract ('Returns a URL the user can open to pay'), plus the trigger and valid tiers. Combined with annotations covering the write/open-world profile, an agent has everything needed to invoke it 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?

Schema description coverage is 100%: the tier enum and the conditional 'required only if the account has no owner email on file' rule are already in the schema. The description's tier list repeats structured data rather than adding new meaning, so the 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+resource ('Create a hosted checkout link to upgrade the OmniForce plan') and enumerates the valid tiers. It is unmistakably different from the read/list siblings (account, geo_scan, list_*), so an agent can pick it without opening the schema.

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?

'Use when a requested feature is blocked by the current plan' gives an explicit trigger condition, which is stronger than implied usage. It stops short of naming when *not* to use it (e.g., already on the target tier) or pointing at an alternative.

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