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

No annotations are supplied, so the description carries the full burden and does so: it declares this is a WRITE, human-gated via elicitation with a before->after diff and approval click, that non-elicitation clients are refused, that dry_run works anywhere, that the write is atomic across tiers, and that Stripe/prices/plan names are untouched. This is exactly the kind of safety and scope context an agent needs before invoking a mutation.

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?

It is long but front-loaded with the core action, and nearly every clause adds operational value (gating, scope, dry_run, follow-up sync). A few clauses could be tightened, but there is little pure 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 4-param, nested, mutation tool with no annotations and no output schema, the description covers authorization, gating, refusal behavior, preview mode, scope limits, and post-write synchronization. An agent has everything needed to call it correctly or avoid it.

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 0% schema description coverage and a nested updates object, the description compensates well: it explains the tier-keyed shape of updates, the -1 unlimited convention, and what dry_run does. It does not explain the mode enum (merge vs replace) or the default, which is the one remaining semantic gap.

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: 'Change the usage limits on an app's existing tiers', with a concrete example (set ai_generations_daily to 200 on pro). It explicitly demarcates itself from siblings by saying it writes ONLY the limits object and that changing prices or adding a tier is a different job handled by create_app_kit or the dashboard.

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 explicit when-to-use (existing tiers, limit keys, -1 for unlimited), when-not ('Changing prices or adding a tier is a different job: use create_app_kit or the dashboard'), and a preview path via dry_run. It also names the prerequisite (elicitation-capable client) and the required follow-up step after success.

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