Save session

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

The description discloses crucial behavioral traits beyond annotations: storage location ('~/.nodriver-mcp/sessions/'), plain-text credential risk ('treat it as a credential'), origin scoping ('Only the current page's origin contributes localStorage'), and the timestamped filename avoiding overwrites. Annotations only declare readOnlyHint false, destructiveHint false, etc., leaving the description to provide the meaningful safety and data-flow 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?

Four sentences, each earning its place: purpose, use case, storage/security, limitation, and alternative. Front-loaded with the main action and objects, no filler or redundant 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 single-parameter tool with an output schema and comprehensive annotations, the description fully covers behavior, security implications, scoping limitations, and the relationship to sibling tools. Nothing essential 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?

The input schema already fully describes the 'name' parameter, including the example 'github-logged-in' and the timestamp append behavior. The description adds no new parameter-specific information, so the baseline of 3 for full schema coverage 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 opens with a specific verb and resource: 'Save cookies, localStorage and open page URLs to a reusable file.' It clearly distinguishes the tool from siblings like load_session (restore) and create_profile (persistent profile) by framing it as the way to keep an interactively obtained login.

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?

Explicitly states when to use: 'This is how you keep a login obtained interactively, so a later run can skip the login flow entirely — restore it with load_session.' It also provides an alternative for a more durable need: 'a persistent profile (create_profile + use_profile) is the sturdier option.' This gives clear when-to-use and when-not-to-use guidance.

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