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

Annotations already declare readOnly, non-destructive, closed-world. Description adds 'free, no signup, deterministic' which is useful context especially deterministic behavior. However, no detail on how unsupported characters are handled, length limits, or idempotency beyond 'deterministic'.

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 concise sentences with zero waste; purpose front-loaded, then notable traits. Well-sized for a simple utility.

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?

Complete enough for a single-parameter, annotation-rich utility with no output schema. Missing edge-case handling details (invalid characters, non-ASCII) that would make it fully complete.

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?

0% schema coverage and the single 'text' parameter is un-described in both schema and description. Description explains the general input ('short string') and output (lowercase ASCII URL slug), which is meaningful, but doesn't clarify the 'text' parameter's constraints. Baseline for 1 param is high, but the coverage gap holds it to a 3.

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 (turn into slug), resource (short string to lowercase ASCII URL slug), and transformation outcome. Distinguishable from sibling penny_url_clean and penny_csv_to_json by the slug conversion focus.

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?

The description implies usage via 'Turn a short string into...' and 'slug', but offers no explicit when-to-use or exclusions vs siblings like penny_url_clean. Free/no signup/deterministic hints at context but not selection criteria.

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