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

With no annotations, the description fully discloses behavior: error on malformed escapes, handling of '+', and the exact output format. It covers edge cases and limitations, making the tool's behavior predictable.

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?

Each sentence adds meaningful information without redundancy. The description is compact yet thorough, covering purpose, behavior, edge cases, and relationship to sibling tools efficiently.

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?

The description is self-contained: it specifies the return format (JSON with 'decoded' key), error behavior, and non-goals, making it sufficient for an agent to use the tool without additional context. No output schema is provided, so this description fills that gap effectively.

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?

Although the schema already describes the 'encoded' parameter, the tool description adds valuable context: it gives an example ('query-string value'), clarifies UTF-8 requirements, and specifies the impact of malformed input, enriching the schema beyond its baseline.

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 clearly states the tool's function: reversing percent-encoding with decodeURIComponent, and explicitly differentiates it from encode_url and other URL-related tools by specifying its scope.

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?

It provides explicit guidance on when to use this tool: as the inverse of encode_url, and clarifies what it does not do (e.g., no Base64/JWT decoding, '+' remains literal), preventing misuse.

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