Set Active Document

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

With no annotations provided, the description carries the full burden, and it does well: it explains the one-of requirement, the exact error condition for ambiguous/absent names, and the fact that only already-open documents can be targeted. It does not describe what happens after success or how an invalid `index` behaves, but the key behavioral traps are disclosed.

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 description is compact, front-loaded with the main purpose, and every sentence contributes either a usage rule or a critical distinction from `open_document`. There is no filler or repetition of schema details.

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 low-complexity tool with 2 optional parameters and no output schema, the description is complete: it states the action, the acceptable identifiers, the error behavior, and the boundary against `open_document`. Nothing necessary for an agent to invoke it correctly is missing.

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 the baseline is 3, but the description adds value by explicitly stating that exactly one of the two parameters must be passed and that `index` is the disambiguation mechanism. This goes beyond the schema's individual field descriptions.

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 uses a specific verb and resource: "Switch focus to an already-open document," and clarifies what the tool is not by pointing to `open_document` for loading files. This cleanly distinguishes it from the sibling tool most likely to be confused with it.

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 description gives explicit usage context: pass exactly one of `index` or `name`, use `index` to disambiguate when `name` matches multiple documents, and use `open_document` instead when the file is not yet open. It does not mention the sibling `set_document`, but the core decision of when to use this vs. the closest alternative is well covered.

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