proj_variables

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

Annotations already establish this is a safe read (readOnlyHint=true, destructiveHint=false), and the description adds genuinely non-obvious behavior: the recursive FB/STRUCT flattening, the resulting instance-path format, and that library-typed variables are collapsed to a single typed item. It omits any mention of the truncation implied by max_array/max_items, but the added behavioral detail is real value beyond annotations.

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 core purpose is front-loaded, the parenthetical example is compact and clarifying, and the scope/library notes follow logically. No filler sentences, though the walk mechanics could be trimmed slightly.

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?

An output schema exists so return values need no explanation, and the core operation is well described. But for a 4-parameter enumeration tool with three undocumented controls governing output size and scope of inclusion, the definition is only adequate.

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 carry all four parameters. It explains scope adequately, but says nothing about max_array (default 64), max_items (default 200000), or include_temp, whose meanings and truncation effects the agent cannot infer from bare integers/booleans.

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+resource: it enumerates 'every variable the project source declares' and describes the exact transformation (flattening to runtime instance paths by walking programs and GVLs through FB/STRUCT definitions), with a concrete example path. This is unmistakably distinct from siblings like proj_interface or proj_search.

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 'scope = one program/GVL/FB to walk instead of all' clause tells the agent how to narrow the operation, which is implicit usage guidance. However, it never names a sibling alternative or states when to prefer this tool over e.g. proj_interface or ads_list_symbols, leaving the routing decision to inference.

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