Read a group's or the selection's grid

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

With no annotations, the description carries the full burden and does so well: it declares read-only, specifies ordering semantics (patch order vs selection order), discloses that selection cells are MAtricks-transformed when MAtricks is active, and notes that distributions follow cells rather than list order. It also states the bridge 0.21.0 prerequisite.

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?

Front-loaded with 'Read-only.' and the branch structure is easy to parse, with each clause earning its place by adding ordering, transformation, or ID-format detail. It is dense but not padded.

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?

There is no output schema and no annotations, yet the description enumerates the returned cell fields (X/Y/Z, PreserveGridPositions, lock, shared cells, bounds, gap count) and the FID/cell-id formats, making it largely self-sufficient. It stops short of fully documenting the return shape, so it is strong but not exhaustive.

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 single parameter has 100% schema description coverage, so the schema already documents that omitting 'group' reads the current selection, which the description restates. Baseline 3 applies since the description adds little semantic detail beyond the schema.

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 read operation on a precise resource (a group's stored fixtures or the current selection, with selection-grid cells). It explicitly distinguishes itself from sibling concepts like gma3_fixtures and gma3_matricks by clarifying that these are selection-grid cells, not physical stage positions.

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 two branches are clearly gated by the 'group' parameter: with a group it reads stored fixtures, without it reads the current selection, and it notes nothing is selected in the group case. However, it never explicitly names an alternative sibling (e.g. gma3_matricks or gma3_fixtures) or states when NOT to use this tool.

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