List sessions

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

Beyond the readOnlyHint/openWorldHint annotations, it discloses the quota (5 open sessions per API key), the idle expiry (closes after 30 minutes without a call), and the filtering rule that closed and expired sessions are excluded. Even the return shape and epoch-millisecond time format are spelled out, which annotations cannot supply.

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?

Every sentence carries distinct information—purpose, return shape, time units, exclusion rule, follow-up usage, and quota/expiry—front-loaded with the primary purpose. No filler or repetition of the title.

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?

No output schema exists, but the description supplies the return structure itself plus units and filtering behavior. Combined with the safety annotations, an agent has everything needed to call it and interpret the result.

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 zero parameters the baseline is high, and the description explicitly confirms 'Takes no arguments,' removing any doubt. There is nothing further to add semantically for an argumentless tool.

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?

States a specific verb and resource ('List the sessions open for this API key') and pairs it with two concrete situations, so an agent can immediately tell it apart from mutation siblings like create_session and close_session.

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?

Gives explicit when-to-use triggers: recovering a lost session_id, or checking how many sessions are open before calling create_session. It also states the no-argument nature and points at the follow-up action (passing the id to any session tool or close_session), leaving nothing to inference.

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