session_start

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

No annotations are provided, so the description carries the full burden. It reveals the tool 'opens a fresh browser tab' and 'starts recording' — some behavioral disclosure — but doesn't say what happens to an existing session, whether the URL is navigated immediately, what start/recording side effects occur, or whether this is destructive to prior state. For a stateful action with no annotation coverage, this is a notable gap.

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?

A single concise sentence, front-loaded with the verb and purpose. Zero wasted words.

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 stateful session-initiation tool with no annotations and no output schema, the description is somewhat thin. It doesn't explain what the agent gains from the 'recording' (observations? trace?), what the expected return indicates, or how session state carries to siblings. But it's a relatively simple 2-param tool that establishes an entry point; adequate overall, with room to improve on session lifecycle expectations.

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?

With 100% schema description coverage, the schema already documents both parameters. The description's 'goal-driven' and 'fresh browser tab' wording adds minimal context (e.g., implying URL is the initial page, goal is the objective), but doesn't meaningfully exceed what the schema describes. Baseline 3 is appropriate.

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 has a clear verb+resource (open a fresh browser tab, start recording) with a specific purpose: goal-driven session. However, it doesn't distinguish itself from session_act/session_observe siblings, though those are clearly different actions (acting and observing within a session, not starting one). The 'goal-driven' qualifier adds useful scope.

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 implies this is the entry point for a session ('start recording'), and the required 'goal' parameter signals that the agent should first define a goal. However, it provides no explicit when-to-use guidance or alternatives, and doesn't mention session_end as the counterpart or any prerequisites.

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