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

Adds substantial context beyond the annotations: early-access status, a required Last Price credential with billing write scope, a concrete failure mode (403 for sandbox keys until the workspace is claimed), and the default mutating behavior that inactive saves rather than sells. It also discloses a side effect the schema only hints at: a code is auto-generated from the name when omitted.

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?

Front-loaded with the core action and its fields, then defaults, then prerequisites, then gating caveats — a sensible order for an agent scanning quickly. The telegraphic phrasing ('a name, price, billing frequency and credits') is slightly clipped, but 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?

For a non-idempotent mutation with 9 parameters and no output schema, the description covers the major unknowns: defaults, auth scope, workspace claim requirement, and code generation. The remaining gap is that it never says what comes back on success (e.g., the created plan and its generated code) or how duplicates/conflicts are handled.

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?

With only 44% schema description coverage, the description carries real load: it explains credits=null means unlimited, defines the two status values behaviorally, and clarifies code defaulting/derivation from name. It leaves billing_frequency's one_time-vs-recurring semantics and the required currency/description fields to the schema, so some required inputs remain thin.

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 credit bundle to sell') and immediately enumerates the defining attributes (name, price, billing frequency, credits). An agent can distinguish it from update_credit_bundle_plan, list_credit_bundle_plans, and grant_credit_bundle_plan without opening any 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?

Gives clear creation-time choices: 'status active puts it on sale now; inactive (the default) saves it to activate later' tells the agent which status to pick for which intent, and prerequisites (billing write scope, claimed workspace) gate the call. It stops short of naming the sibling to use for later changes (update_credit_bundle_plan) or for assigning bundles to customers (grant_credit_bundle_plan).

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