set_run_font

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

The description states the tool sets the font, but with no annotations provided, it lacks details on error handling (e.g., what if the run index is out of bounds or font name is invalid), side effects (e.g., overwriting existing font), and whether the operation is reversible. The basic behavior is clear, but essential behavioral traits for a mutation tool are missing.

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?

The description is short and well-structured with a summary line followed by a labeled parameter list. It avoids redundancy and unnecessary details. However, the parameter definitions could be slightly more compact by omitting parameter names (already in schema), though this is a minor issue.

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?

Given the tool's simplicity and the presence of an output schema (which may describe the return value), the description covers the core functionality. However, it lacks contextual guidance such as how to obtain the required para_id or run_idx (e.g., using get_runs), and does not mention limitations (e.g., font must be installed). It is adequate but not comprehensive.

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?

The schema has 0% description coverage, so the description bears the full burden for parameter semantics. It provides concise definitions for each parameter: para_id is 'paraId of the target paragraph', run_idx is 'Zero-based index', and font_name includes an example ('Arial'). This adds significant value beyond the schema's bare titles, justifying a score above 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 action ('set'), the resource ('font of a specific run'), and the context ('in a paragraph'). It also specifies the run index is zero-based, which distinguishes it from tools that might use one-based indexing. Among sibling tools like set_run_color or set_run_size, this tool's 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?

The description does not provide explicit guidance on when to use this tool versus alternatives like set_formatting or clear_run_formatting. While the tool name implies its usage is for setting font only, there is no mention of prerequisites (e.g., using get_runs to find the run index) or exclusions. Usage is implied but not explicitly outlined.

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