pane_focus

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

No annotations are provided, so the description carries the full behavioral burden, and it does disclose the key trait: STATE_MUTATING focus change plus a precondition that the index must be valid within pane_list. It does not mention error behavior for an out-of-range index or whether focus persists across commands, keeping it below 5.

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?

One sentence of purpose followed by labeled WHEN TO USE / SIDE EFFECTS / LIMITATIONS clauses — front-loaded, scannable, and every line adds information.

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 state-mutating tool with no annotations and no output schema, the description covers purpose, timing, mutation side effect, and validity constraint. Only the failure mode for an invalid index is unaddressed.

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% and the single parameter is already documented as '(0-based, from pane_list)'; the description's 'index (0-based)' restates rather than extends that. Baseline 3 applies when the schema does the work.

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 gives a specific verb + resource + scope: 'Switch active user focus to a specific chart pane by index (0-based).' That is enough to distinguish it from pane_list (read) and pane_set_symbol (content change), though it never explicitly contrasts itself with those siblings.

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?

A dedicated 'WHEN TO USE' clause states the triggering condition: call it before chart operations aimed at a secondary pane in a multi-chart layout. It lacks an explicit when-not or a named alternative, so it stops short of a 5.

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