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

With no annotations, the description carries the full burden; it does disclose genuine behavior beyond the schema: free tier, rate limiting, non-mutation of payment-critical values. But it omits error/invalid-payload behavior, what the rate limit actually is, and whether normalization mutates or returns a new payload.

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?

Two tight sentences with the key guarantee front-loaded after the purpose clause; no filler. Slightly dense with unattributed modifiers ('Free, rate-limited') but appropriately sized.

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?

No output schema and no annotations, with a nested free-form payload object and an undocumented required target_service string. An agent cannot reliably construct a valid invocation from this description alone; payload shape, service identifiers, and failure behavior are all missing.

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 0%: the nested 'payload' object has no field documentation, and 'target_service' is never mentioned in the description at all, so its expected values are entirely unknown. The description adds some intent ('payment-critical values are never changed') but does not compensate for the uncovered, required parameters.

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 action pair (validation and safe key normalization) on a specific resource (payload) with scope (before payment). The adjectival 'Free, rate-limited' implicitly distinguishes it from the sibling schema_normalize, but the distinction is left for the agent to infer rather than stated.

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 timing context ('before payment'), which implies when to reach for it, but never names the alternative schema_normalize or states when to use the paid variant instead. No exclusions or prerequisites are given.

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