list_layers

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

With no annotations supplied, the description carries the full burden, and it does describe the observable output in concrete terms: geometry type, SRID, approximate row count, extent, and column names. The 'approx.' qualifier usefully sets expectations about precision. It does not disclose result-size limits, pagination, or schema-privilege requirements for a tool that could scan an entire database.

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, zero waste, with the entry-point cue front-loaded before the capability statement and the narrowing hint. Every clause conveys information an agent needs.

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 two-optional-parameter read tool with no output schema and no annotations, the description is nearly self-sufficient: it explains purpose, returned fields, and filtering. The remaining gap is output volume behavior (how many layers are returned, whether results are capped) for large geospatial catalogs.

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 both parameters are already fully documented ('Only layers in this schema', 'Case-insensitive text matched against layer and column names'). The description's note about searching by name/column with examples like 'road' and 'population' largely restates the schema, adding only illustrative examples, so baseline 3 applies.

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?

States a specific verb and resource ('List the spatial layers') and immediately narrows scope to 'geometry/geography tables & views', then enumerates the returned fields (geometry type, SRID, row count, extent, column names). 'START HERE' positions it as an entry point relative to the other 13 sibling tools.

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?

'START HERE' plus the instruction to use the search argument for name/column lookups gives clear context about when to call it and how to narrow the result. It stops short of naming when to move on to describe_layer or find_features, so the agent must infer the downstream workflow.

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