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

With no annotations, the description carries the transparency burden and uses it well: it restricts results to 'active' sessions, lists sample return fields, and calls out the non-obvious behavior that API-key calls mark no session as is_current. It could also explicitly state that the operation has no side effects, but 'list'/'shows' already imply a read-only call.

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 core purpose is front-loaded in the first sentence, and the API-key caveat and access note follow in four compact sentences. The ACCESS block is client-specific but earns its place because it is a hard prerequisite for calling the tool successfully.

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 parameterless list tool with no output schema or annotations, the description covers purpose, scope, sample fields, access requirements, and a runtime caveat. The only minor gaps are the exact full response shape and behavior when unauthenticated, which are not critical for tool selection.

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 input schema is empty and schema description coverage is 100%, so there are no parameter semantics for the description to add. The 0-parameter baseline applies, and the text introduces no parameter-related confusion.

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 specific verb and resource: 'List all active authentication sessions for the current user', and names the relevant output fields (channel, user agent, expiry). This scope plus the plural 'all' distinguishes it from sibling tools like get_session, list_api_keys, and revoke_auth_session even though none is named.

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?

It gives explicit when-to-call context: authenticate the MCP client first, then call the tool. It also states a clear when-not/operational caveat: 'start_login does NOT open this tool.' It stops short of a 5 because it does not point to an alternative tool for single-session lookups or other similar cases.

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