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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds the prerequisite gating and the 'free Brainstem' framing, but says nothing about what the tool returns or how the guidance is delivered, so it adds only moderate context beyond annotations.

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?

Two tight sentences with no waste; the optional/later framing and the prerequisite are front-loaded where an agent will see them before deciding to offer the tool.

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 read-only instructional tool with two optional params and no output schema, the description covers the essential decision context. It could note that the result is guidance text to relay to the user, but nothing needed to call 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 description coverage is 100%, with both optional params (os enum, filename) fully documented in the schema. The description adds no syntax or format detail for either parameter, so the baseline 3 applies.

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 states a specific resource and scope: instructions for keeping an agent running on the user's own computer via the free Brainstem. It implicitly distinguishes itself from siblings like use_agent_here and get_agent_code by being the local-hosting guide, though it never names those siblings explicitly.

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?

Gives a clear timing condition ('Optional, for later') and a prerequisite ('Only offer this after the user has used the agent in the chat and wants to keep it'). It does not name alternative tools for related needs, 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.