session_fixture

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

The description adds significant behavioral context beyond annotations: it states that save overwrites without asking, restore writes on top without clearing first, restore refuses on different origin, and name is required except for list. Annotations already indicate destructiveHint=true and idempotentHint=true, but the description clarifies the specifics.

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 three sentences, front-loaded with the primary purpose and common use case. Every sentence provides essential information without redundancy. The structure is efficient and easy to parse.

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 complexity (3 parameters, no output schema, annotations present), the description covers key behaviors, edge cases (different origin), and default behavior for tab_id. However, it does not describe what the list action returns, which might be helpful for an agent.

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% with descriptions for all 3 parameters. The description adds further meaning: it explains that name is required except for list, and tab_id omitted means the last navigated tab. It also clarifies the action enum values (save/restore/list). Thus it enriches beyond the schema.

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 function: snapshotting localStorage, sessionStorage, and cookies into a named server fixture, restoring one, or listing saved fixtures. It specifically mentions 'A logged-in state is the usual reason,' which distinguishes this from sibling tools like get_storage or set_storage that operate directly on browser storage.

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 the tool (for saving/restoring logged-in states). It also details important behaviors like overwriting without asking for save, writing on top for restore, and refusal on different origin. However, it does not explicitly mention when not to use or provide alternatives, though the context makes it apparent.

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