brain_session_list

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

Annotations already declare readOnlyHint and idempotentHint, so the safe read-only nature is established. The description adds meaningful behavioral context beyond those annotations: the server only auto-opens/closes an agent tracer session, and hooks/auto-close must never invoke this boundary. This is valuable context, though it does not describe list ordering, pagination, or return shape.

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?

Two short sentences with no filler. The primary action is front-loaded, and the critical invocation restriction is placed in the supporting sentence. Every sentence earns its place.

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 description fully covers the unusual invocation policy, which is likely the highest-risk aspect of this tool. However, with no output schema and no parameter descriptions, the agent still lacks context about what a session entry contains, which status filters mean, and what the list response looks like. Adequate for basic invocation but with meaningful gaps.

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 0%, and the description does not compensate for any of the four parameters. The schema provides names, types, defaults, and the status enum, but meanings like 'stale', 'abandoned', and 'closed_inactive' are left unexplained, and project_key semantics are not addressed. With zero coverage, the description should add parameter context but does not.

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 states a clear verb and resource ('List sessions') and adds a distinctive policy constraint: it runs only on explicit user command. It does not explain what kinds of sessions are returned or how this differs from sibling read tools, but the core purpose is unambiguous.

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 gives an explicit when-to-use condition ('only in response to an explicit user command') and an explicit when-not-to-use condition ('no hook and no auto-close may invoke this lifecycle boundary'). It does not mention sibling alternatives, but the trigger and exclusion are clear enough for an agent to decide.

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