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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond them: it discloses that transliteration/normalization happens locally and warns to verify preferred slugs before publishing permanent URLs, a behavioral caveat not present in the structured fields.

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?

Three short sentences, all front-loaded: what it does, when to use it, then the sibling exclusion and behavioral caveat. 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 simple pure-function generator with 100% schema coverage and no output schema, the description is nearly complete: it names the output (Unicode-aware slug) and the local-processing behavior. It stops short of describing edge-case output (e.g. truncation at maxLength or empty input), which leaves a small gap.

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 the schema already documents both `text` (with a Café example) and `maxLength` bounds, so the description carries no additional parameter syntax or format detail. Baseline 3 is appropriate when the schema does the heavy lifting.

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 and resource ('Produce Unicode-aware slug from a title') and immediately scopes it against the sibling is-url-safe, so an agent can distinguish it from the other generate-* tools without opening a 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 an explicit trigger ('Use when creating an SEO-friendly path segment from a title') and names the alternative for the adjacent case ('To check an existing full URL, use is-url-safe instead'), which is the exact when/when-not/alternative pattern that routes correctly.

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