set_expression

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

With no annotations, the description fully carries the burden and does an excellent job. It discloses the mutating nature, undoability, language validation behavior (hscript/python with status=error for invalid values), and its classification as not read-only/no-undo. This gives agents essential behavioral context beyond the schema.

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 concise and front-loaded with the core action. It uses structured formatting for the language parameter and includes essential caveats in three sentences. Minor noise includes the cryptic 'PR 19' reference, but overall it is well-organized and efficient.

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 covers mutating behavior, undo, language validation, and undo group policy, which is good. However, it does not explain return values or success/error response structure (e.g., what a typical output looks like). Given the lack of an output schema, this is a notable gap for an agent to infer results.

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 0%, so the description must compensate. It only explains the 'language' parameter's allowed values and mapping to hou.exprLanguage. Other key parameters (ctx, path, parameter, expression) remain unexplained, leaving the agent to guess their meaning. This is insufficient for a 5-param tool.

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 '写入 parm 表达式' (write parm expression), specifying a specific verb and resource. It distinguishes from siblings like get_expression (read) and set_parameter (set value) by focusing on expression writing, with additional context about persistence and undoability.

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 provides clear context that this command is for parameter channel data writes and is not read-only or no-undo. It implicitly differentiates from read tools like get_expression and other mutating tools by mentioning undo group policy. However, it does not explicitly name alternative tools or provide 'when not to use' guidance.

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