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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the 'Read-only' clause is largely redundant. However, the description goes beyond the annotation by disclosing the concrete shape of the result (count, total, decline reasons, most recent failures with customer email) and the 'recent window' scoping, which is real behavioral context. It stops short of covering auth/connection requirements or rate limits.

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?

A single sentence with a colon-delimited payload list; the resource is front-loaded and the 'Read-only' safety note is placed last. No filler sentences, though the enumeration makes it dense to parse in one pass.

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?

There is no output schema, so the description carries the burden of explaining return values, and it does so reasonably: counts, totals, decline reasons, and recent failures with emails. Minor gaps remain — currency, whether multiple Stripe accounts are aggregated, and whether the count/total is computed over the same window as the listed failures.

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%, so the schema already documents both 'days' (1-365, default 30) and 'limit' (1-50, default 10). The description only gestures at 'a recent window' and 'the most recent failures' without adding syntax, defaults, or tradeoff guidance, so 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?

The description names a specific resource (failed card and payment charges in the user's Stripe account) and enumerates what the tool returns: count, total amount, decline reasons, and recent failures with customer email. That is far more specific than a bare name restatement and separates it in spirit from stripe_mrr_summary and stripe_churn_summary. It does not explicitly name a sibling it should be preferred over, which keeps it from a 5.

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?

Usage is implied by the described output (you want failure counts, decline reasons, recent failing customers) and the 'recent window' framing, but there is no explicit when-to-use statement. It never tells the agent when to prefer stripe_api_read or stripe_api_search over this summary, nor any prerequisites such as needing a connected Stripe account, so the agent must infer routing.

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