Galaxy Brain

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. While it mentions creating a branch 'without losing your current train of thought,' it doesn't specify whether this is a read-only or destructive operation, what permissions are required, how branches interact with the original session, or what the output looks like. For a tool that likely mutates session state, this is a significant gap in behavioral context.

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 two sentences, front-loaded with the core purpose and followed by a concise usage guideline. Every word earns its place, with no redundancy or fluff. It's appropriately sized for a tool with clear functionality and good schema coverage.

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 moderate complexity (creating a branch in a thinking session), lack of annotations, and no output schema, the description is minimally adequate. It explains the purpose and usage context but lacks details on behavioral traits (e.g., mutability, side effects) and output format. The schema covers parameters well, but overall completeness is limited by missing behavioral and output information.

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%, so the schema already documents all four parameters (session_id, branch_from, branch_name, first_thought) with clear descriptions. The description adds no additional parameter semantics beyond what's in the schema, such as explaining the relationship between 'branch_from' and the new branch or how 'first_thought' initializes the branch. Baseline 3 is appropriate when the schema does the heavy lifting.

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's purpose: 'Create a new branch to explore an alternative approach.' It specifies the verb ('Create') and resource ('branch'), and distinguishes it from siblings like 'revise' or 'think' by focusing on parallel exploration rather than modification or continuation. However, it doesn't explicitly differentiate from all siblings (e.g., 'start_thinking' might also initiate new thought paths).

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 provides clear context for when to use this tool: 'Useful when you want to try a different direction without losing your current train of thought.' This implies it's for parallel exploration rather than linear progression. It doesn't explicitly state when not to use it or name alternatives among siblings, but the context is sufficiently clear for an agent to infer appropriate usage.

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