count_features

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly states the count operation, which implies a read-only query, but it does not explicitly confirm no side effects, error behavior for invalid layer names, or how the count is computed. The core behavior is transparent, but additional context is missing.

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 two sentences with no filler: it states the action first, then the one parameter. Every line earns its place and the format is easy for an agent to scan.

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 single-parameter count tool with an output schema, the description covers the essential invocation details. It could be slightly richer by explicitly stating that it returns a numeric total or that the operation does not modify the layer, but these are minor given the simple scope and presence of an output schema.

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 fully compensates by documenting the only parameter. 'Exact layer name as shown in the Contents pane' adds crucial real-world meaning that the bare 'Layer' title in the schema lacks.

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 states a specific verb ('Count') and resource ('features (rows) in a layer'), making the tool's purpose unambiguous. It is clearly distinguishable from siblings like list_layers or get_layer_features, which list or retrieve rather than return a count.

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 implies this tool is for getting a total feature count, but it does not explicitly state when to use it over alternatives or mention situations where another tool would be preferred. There is no exclusion or comparison guidance, so the agent must infer usage from the tool name and description.

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