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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, so the safety profile is covered. The description adds essentially nothing beyond that — no mention of behavior on malformed input, whether encoding is safe to re-run on already-encoded text, or which characters each mode escapes.

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 efficient sentence with the operations front-loaded and parse's outputs at the tail. No filler, though it spends words enumerating parse fields that the output schema already covers.

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?

With an output schema present, return values need not be explained, and safety hints are covered by annotations. However, for a 4-param tool at 25% schema coverage the key gaps — mode semantics and error handling for invalid percent-escapes — are left unaddressed.

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 only 25%: only plusAsSpace is documented. The description does not explain 'mode' (component vs full) or clarify the action enum's interaction with mode, which is the central semantic choice for this tool. It adds only marginal meaning over the schema.

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 specific operations (percent-encode, decode, parse) and the resource (text / URL), and even enumerates parse outputs (host, path, hash, query parameters). It does not explicitly contrast itself with adjacent siblings like base64_codec, but 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?

No guidance on when to choose encode vs decode vs parse, nor on the component vs full mode distinction. The stated default in the schema is 'parse' while the description leads with encode/decode, which could misroute an agent. Nothing tells the agent when to prefer this tool over base64_codec or convert_curl.

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