add_field_with_values

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

With no annotations, the description must fully disclose behavior. It reveals the atomic rollback on expression failure, which is important. However, it omits whether the operation modifies the original layer, permission requirements, side effects, or return value structure.

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?

Two sentences with minimal fluff. The first sentence front-loads the core action. The second adds crucial atomicity detail. Could be slightly more structured (e.g., bulleted types) but is 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?

For a tool with 6 parameters, no schema descriptions, and an existing output schema, the description covers the operation's unique behavior (atomicity, type options) but fails to explain parameters like length/precision or output. It's adequate but not fully complete.

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 'type' parameter's allowed values. Other parameters (name, expression, layer_name, length, precision) receive no additional meaning beyond the schema's basic type/defaults.

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 it adds a new field and populates it from a QGIS expression in one step. It lists valid types and describes atomicity. This distinguishes it from sibling tools, none of which perform field addition.

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?

No guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, trade-offs, or cases where it's inappropriate (e.g., existing field names). The default type and length/precision defaults are implied but not explained.

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