session_list

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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds value beyond annotations by disclosing the response scope — both raw gateway session records and the per-provider active session — plus the optional filtering behavior. No contradiction with 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?

A single sentence that front-loads the verb, states the resource scope, and appends the optional filter. Every clause earns its place and there is no fluff, redundancy, or filler.

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 low-complexity tool with one optional enum parameter and a full annotation safety profile, the description covers the operation, the output scope, and the filter. Since there is no output schema, the 'records and active session per provider' phrasing partially compensates by indicating the return categories, though exact record shape is unspecified.

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% — the 'cli' parameter is fully documented in the schema with its enum values. The description merely restates that filtering by provider is optional, reinforcing the schema without adding syntax or format detail. This meets the high-coverage baseline of 3 but does not exceed it.

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 ('List') and a specific resource ('gateway session records and the active session per provider'), making the tool's function immediately clear. Its collective listing scope inherently distinguishes it from the session mutation/retrieval siblings (session_create, session_delete, session_get, session_set_active) and the per-provider active-session detail is a unique identifying feature.

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 'optionally filtered by provider' clause gives useful context for when the sole parameter applies, and the 'List' verb implies this is the browse/inspect tool among session_* siblings. However, it never explicitly states when to prefer this over session_get or when not to use it, and no alternative is named.

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