merge_layers

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

The description goes well beyond annotations by disclosing reprojection behavior, null-filling of missing columns, provenance manifest recording, feature count verification, and refusal of inputs without a CRS. It also warns about the silent-error risk of measured-looking absent data. No contradiction with annotations exists.

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 purpose is front-loaded in the first sentence, and every following sentence adds a distinct, important behavioral fact. The extended caveats about null-filling and CRS handling are necessary for correct use, not filler.

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 moderately complex data-merging operation with only two parameters and an output schema available, the description covers the key conditions, failure modes, and relationships to sibling tools. Nothing essential is missing for an agent to invoke it correctly.

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 provides only names and types, so the description carries the semantic burden. It meaningfully clarifies that input_paths expects two or more layers and that the operation writes to output_path, while also explaining processing details like CRS reprojection. It doesn't explicitly bind each parameter name, but given only two parameters that map naturally, this is a strong-enough compensation for 0% schema coverage.

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 opens with a specific action: 'Append two or more layers into one', clarifies schema union and attribute alignment, and explicitly distinguishes itself from a geometric union. This makes the tool's purpose unmistakable and separates it from siblings like dissolve_layer.

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 usage context: layers are reprojected to the first layer's CRS, inputs without CRS are refused, and it explicitly tells the agent to use dissolve_layer for geometric merging instead. This is exemplary when-to-use versus 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.