create_vex_expression

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

With no annotations, the description carries the full burden and does disclose real behavior: expressions are evaluated before being kept, invalid expressions are discarded ('not kept'), and VEX attribute syntax triggers a refusal naming an alternative tool. It does not say whether an existing expression is overwritten or what is returned on success.

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?

Front-loaded with the core action and the two key constraints before the Args block. The Args list largely restates the schema field names, so a little space is spent on low-yield content, but nothing is padded or buried.

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 parameter-mutating tool with no annotations and no output schema, the critical unknowns an agent faces (HScript vs VEX, failure semantics) are answered. Remaining gaps are secondary: overwrite behavior for an already-expressioned parameter and permission requirements.

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, and it does so only minimally: node_path and parm_name get tautological glosses ('Path to the node', 'Parameter name'). The one high-value addition is that vex_code is HScript syntax despite its VEX-sounding name, which offsets the gap partially but not fully.

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 first sentence states a specific verb and resource ('Set an HScript expression on a parameter') plus evaluation timing ('evaluated before it is kept'), which resolves the confusing name (a 'vex_expression' tool that actually sets HScript). It differentiates from the VEX path by naming create_wrangle, though it never distinguishes itself from the near-identical sibling set_expression.

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?

It gives an explicit when-not and a routing alternative: parameters cannot run VEX, '@' syntax is refused, and the error points to create_wrangle. What is missing is positive guidance on when this should be preferred over set_expression or execute_hscript.

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