end_session

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

Annotations only declare readOnlyHint=false, openWorldHint=false and idempotentHint=true. The description adds the key behavioral facts the annotations omit: what is destroyed (output-directory setting and held plots), that termination is optional because sessions self-expire, and the follow-up requirement to re-create a session.

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 short sentences, the destructive effect front-loaded, then optionality, then the follow-up requirement. No filler or redundant restatement of the tool name.

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?

A simple one-parameter lifecycle tool with no output schema and adequate annotations; the description covers the effect, destructiveness, optionality, and postcondition, leaving nothing an agent needs before calling it.

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% and the session_id parameter is thoroughly documented in the schema itself (identity semantics, privacy, reuse across calls, re-creation on expiry). The description adds no parameter-level detail, so the baseline 3 is appropriate.

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?

Specific verb+resource ("End a session") plus the exact consequences of the action (discards the output-directory setting and all plots it holds). An agent can distinguish this from sibling create_session without opening either schema.

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?

Explicitly states when to call it ("when the user is done, to free server memory promptly") and when it is unnecessary ("Optional — sessions also expire on their own"), plus the postcondition that a new create_session() is required for further calls. The alternative to calling it is named.

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