Set Active Document

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

Discloses error conditions for `name`, explains the 0-based list index, and clarifies the tool only switches between already-open documents. No annotations are provided, so the description fully covers behavioral traits.

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?

Three sentences, each earning its place: first states purpose, second explains parameters and constraints, third clarifies scope vs alternative. No redundancy.

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?

Given the tool's simplicity (switching focus with two optional parameters), the description is complete. No output schema exists, but the tool likely returns success/failure - not crucial to describe.

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 coverage is 100%, so baseline is 3. The description adds value by explaining the error behavior of `name` and the disambiguation role of `index`, enriching the schema beyond simple definitions.

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 clearly states the tool switches focus to an already-open document using `index` or `name`. It distinguishes from sibling `open_document` by noting this works only on open documents.

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?

Explicitly says to pass exactly one of `name` or `index`. Warns that `name` errors on ambiguous matches and suggests using `index` to disambiguate. Also advises using `open_document` for loading files from disk.

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