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

Annotations declare readOnlyHint=false, idempotentHint=false, openWorldHint=true, and the description proactively explains the seeming contradiction ('not marked read-only because each call is charged'). It also discloses pricing, the 25-free tier, and that failed calls are free — real behavioral context beyond the annotations. It does not describe output format or rate limits, keeping it below 5.

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 transform, then usage, then an example, then commercial terms. Dense and largely waste-free, though the pricing/payment sentence is long and slightly interrupts the technical flow.

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 must carry the return contract; it shows a concrete example output ('Crème Brûlée & Straße!' → slug), which mostly covers this. Behavior, cost, and the annotation rationale are all present, leaving little an agent needs that is 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 coverage is 100% and already documents both parameters, so the baseline is 3. The description adds value by clarifying semantics ('- by default') and providing a worked example that demonstrates accent handling with the separator, which the schema does not.

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 ('Turn any text into a URL-friendly slug') and enumerates the transformation rules (accent folding, lower case, separator substitution). The sibling list contains adjacent string utilities (case, url_encode), but none are sluggers, so the purpose is unambiguous.

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 for file names, URLs and IDs' gives clear intended contexts. It does not, however, name an alternative or a when-not-to-use case against siblings like case or url_encode, so it stops short of full routing guidance.

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