invariance_session_list

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description need not restate that this is a read-only operation. It adds some behavioral context by explaining what the source enum means, but does not disclose additional traits like pagination, ordering, or result structure. The description does not contradict the annotations.

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 two sentences long, with the core purpose and filters front-loaded in the first sentence. The second sentence offers three concrete, distinct examples that immediately clarify real-world use, with zero filler or 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?

For a straightforward list operation with no output schema and read-only/open-world annotations, the description gives enough to decide when to call it and what filters to apply. It does not state the return format (e.g., a list of session objects) or any pagination behavior, but these are typical for such tools and not critical for correct invocation.

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 schema description covers source (with enum meanings) and status (with an example), but run_id and agent_id have no descriptions. The description mentions 'filtered by source, agent, run, or status' but adds no meaning for the undocumented parameters. With 50% schema coverage, the description fails to compensate for run_id and agent_id, though source is well-documented in the schema itself.

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 clear verb and resource: 'List agent-sessions' and enumerates the optional filters (source, agent, run, status). The concrete examples (source="api" for Claude Code work, source="meeting" for meetings, source="screen_recording" for human teammates) immediately distinguish it from sibling list tools like invariance_run_list and invariance_node_list, which target different entities.

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 provides three explicit, scenario-based usage examples ('Use this to find...'), which tell the agent when to invoke this tool. However, it does not explicitly contrast with alternatives or state when NOT to use it, leaving the agent to infer that session listing is the right choice for these scenarios rather than run or node listing.

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