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

With no annotations provided, the description fully discloses the behavioral profile: it is read-only, frozen, writes nothing, is marked [FREE], and explains that snapshot_id changes signal world drift. This goes beyond the bare schema and gives the agent a clear mental model of side effects and re-fetch semantics.

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 and every sentence earns its place: first the core identity and contents, then the no-write guarantee, then the concrete workflow. It is front-loaded with the most important signal ([FREE] read-only snapshot) and avoids any filler or repetition.

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 zero-parameter tool with an output schema, the description is complete: it lists the returned domains, states safety/cost behavior, and explains how to use it with sandbox_simulate including the drift-check pattern. Nothing essential is missing for an agent to call and interpret this tool correctly.

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?

The tool has zero parameters and 100% schema coverage, so there is no parameter burden for the description to carry. The baseline of 4 applies; the description additionally clarifies what kind of data is returned, which is the relevant semantic context for a parameterless snapshot tool.

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 opens with a specific, concrete definition: 'A frozen, read-only snapshot of the AgentWorld world' and enumerates exactly what content is included. It clearly differentiates itself from mutation tools like sandbox_simulate by emphasizing 'Nothing is written,' and the tool name plus listed contents make its resource unmistakable.

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 timing: 'Use it before sandbox_simulate(), and re-fetch afterwards to check whether the world moved.' This is strong contextual guidance tied to a sibling tool. It does not explicitly state when not to use it or name alternative read-only data tools, so it falls just 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.