ACTION_TEXT_OPERATION

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

With no annotations supplied, the description carries the full burden and discloses several non-obvious traits: split returns a newline-joined string rather than an array, string parameters accept ${var} interpolation, and results come back as a variable snapshot JSON with the default output name text_output. It does not explain how errors interact with on_error or the node timeout, leaving that to 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?

Front-loads the operation list, then the output contract, then the caveats, which is the right order for scanning. It is dense but nearly every clause carries information; the doubled '。。' punctuation and the slightly redundant 'output: text_output' / 'results returned as variable snapshot JSON' pairing are minor blemishes.

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?

There is no output schema, so the description must cover return behavior, and it does: named result variable, snapshot JSON shape, and the surprising string-vs-array split result. Combined with a fully documented 12-parameter schema, an agent has enough to call this correctly; only error-path semantics are left implicit.

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%, so the baseline is 3, but the description adds meaning the schema does not: all string parameters support ${var} interpolation and the result variable defaults to text_output. It adds nothing about start/end indexing beyond what the schema already documents, so it sits just 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?

Opens with a specific resource (text) and enumerates the exact operations (replace, substring, split, case conversion, trim, concat) that map onto the action enum. It also explicitly distinguishes itself from ACTION_ARRAY for the array-producing case, so an agent can separate the two without reading either schema.

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?

Gives an explicit routing rule for the one ambiguous case: if a real array is wanted rather than a newline-joined string, use ACTION_ARRAY (action=set). It does not cover when to prefer ACTION_PARSE_JSON, ACTION_SET_VARIABLE, or ACTION_ASSERT for related string work, so the guidance is clear but not exhaustive.

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