Living Stack: session_start

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

Annotations only supply readOnly=false, idempotentHint=false, and destructiveHint=false. The description adds valuable behavioral context by disclosing that the session is isolated and that scope and budget are immutable, which are meaningful guarantees beyond the structured annotations. It does not contradict any annotation.

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 a single front-loaded sentence with no redundant words. It states the core action and the most important constraints without padding.

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 presence of an output schema, detailed parametter descriptions, and annotations, the description is largely complete for starting a session. It conveys the essential isolated and immutable nature of the session, though it could have briefly mentioned retention or cost behavior to fully round out the context.

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%, so the baseline is 3. The description adds extra semantic meaning by stating that scope and budget are immutable, which clarifies the behavior of the scope and budget_limit_usd parameters beyond their schema descriptions. It does not explain every parameter, but the schema already covers them.

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 uses a specific verb "Start" and a clear resource "isolated proof session," with distinctive qualifiers "immutable scope and budget." It is immediately distinguishable from sibling tools like session_close, status, and check_claim, which perform different lifecycle or inspection actions.

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 the tool should be used when a new isolated proof session is needed, but it does not explicitly state when to prefer it over alternatives or mention exclusions. It is not misleading, just minimally guiding.

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