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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds the useful detail that output is pretty-printed JSON, but says nothing about error behavior for malformed/unsupported TOON input, which is the main behavioral risk for a decoder.

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 front-loaded sentence with zero filler; the action, input, and output format are all conveyed without waste.

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 trivial one-parameter conversion tool with no output schema, the description tells the agent the input type and the exact return format, which is essentially everything needed to call it. Only the failure mode for invalid TOON input is 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 100% for the single 'toon' parameter, so the schema fully documents the input. The description adds no syntax, format, or encoding detail beyond what the schema already states, making the baseline 3 appropriate.

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 (Decode) and resource (a TOON document) plus the output format (pretty-printed JSON), which makes the direction of conversion unambiguous. It never names the sibling json_to_toon, so the differentiation is implicit rather than explicit, but 'back to JSON' makes the inverse relationship clear.

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?

Usage is implied by the direction stated in the description and the tool name; an agent can infer this is the TOON→JSON path. There is no explicit when-to-use statement, no mention of when not to use it, and no reference to the json_to_toon alternative.

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