session_create

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

With annotations containing only a title, the description carries the transparency burden. It discloses that the session is persistent, stateful across page transitions, returns a session_id, and has an 8-minute idle timeout. It does not mention resource/cost implications or explicit close expectations, but covers the key lifecycle traits.

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?

Three sentences, each carrying distinct information: what the session is, when to use it, and what it returns and how long it lives. The main purpose is front-loaded and there is no redundancy.

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?

The definition tells the agent what the tool does, when to choose it, what it returns, and how long it lives, which is sufficient for a creation tool with no required parameters. It could explicitly state that the returned session_id is consumed by the other session_* tools, but the siblings and context make that inferable.

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%, so the baseline is 3. The description only contributes 'persists 8 min idle,' which aligns with the default ttl_secs=480, but it does not add semantics for cookies, storage, or proxy beyond the schema. This is adequate given the schema's completeness.

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 ('Create a persistent interactive browser session') and enumerates the interaction types it supports. The final sentence 'rather than read it once' separates it from read-only siblings like fetch/search, so an agent can distinguish it without opening schemas.

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 'Use when...' sentence is explicit about the conditions for choosing this tool—login flows, forms, pagination, click-through—and implicitly rules out one-shot reads. A named alternative is absent, but the read-vs-interact contrast gives clear selection guidance.

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