text_applyCharStyle

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

With no annotations, the description carries the full behavioral burden. It says 'apply' but does not disclose whether an existing character style on the range is overwritten, whether an unknown styleName errors or is created, whether the document is saved, or what the response contains. Only the targeting scope is conveyed.

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. It is concise and well-structured, though its brevity reflects under-specification rather than disciplined economy.

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 6-parameter mutation tool with 17% schema coverage, no annotations, and no output schema, the description leaves major gaps: style existence requirements, overwrite behavior, story/paragraph coordinate semantics, and error handling are all 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 17% – only document_id is documented. The phrase 'range of characters within a paragraph' loosely hints at startChar/endChar/paragraphIndex, but storyIndex, styleName validity, and the endChar/startChar offset conventions (0-based start, 1-based end minimum) are left entirely to the schema's bare types.

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 states a specific verb and resource ('Apply a character style') plus the exact scope ('a range of characters within a paragraph'), which is enough to distinguish it from the sibling text_applyParagraphStyle. It stops short of naming that sibling explicitly, so it earns a 4 rather than a 5.

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?

There is no when-to-use guidance, no prerequisites (e.g. that the style must already exist via style_listCharacter/style_createCharacter), and no mention of the alternative text_applyParagraphStyle or text_applyFont. The agent must infer routing entirely from the name.

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