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

With no annotations provided, the description carries the behavioral disclosure burden. It discloses the auth verification step, the session creation side effect, payload serialization/defaulting, the JWT response with subject=internal session id, a 1-hour TTL implementation detail, and best-effort email persistence. This is substantial and transparent, though it stops short of describing error behavior or idempotency.

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 well-organized: core behavior first, then side effects and alternative routing, then source and configuration guidance. It is dense but each sentence contributes useful information. Slight redundancy exists between 'Requires auth.firebaseToken' and the earlier 'Verifies Firebase ID token', but overall it is structured effectively.

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?

Given the tool has no output schema, the description explains the key return value (sessionToken JWT) and includes source endpoint, auth requirements, TTL, side-effect email persistence, and a routing alternative. It lacks error scenarios and response envelope details, but it is sufficient for an agent to select and invoke the tool correctly.

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 has 0% coverage per the context signal, so the description must compensate. It adds meaning for payload (serialized, defaults to {}), auth.firebaseToken (verified and sent as Bearer), and connection.workspaceName/appId (preferred stable config). However, it does not add detail about body.app_id beyond what the schema itself already says, and it omits guidance for host, so compensation is partial.

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 clearly states it verifies a Firebase ID token, creates a session for workspaceName, stores payload, and returns a sessionToken JWT. It also distinguishes itself from post_sessions_get_or_create by explicitly mentioning that the alternative should be preferred for hosted-login-style flows, making sibling differentiation strong.

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 gives explicit routing guidance: 'Prefer POST /sessions/get-or-create for hosted-login-style flows that should reuse an active session.' It also provides operational prerequisites such as requiring auth.firebaseToken and forwarding it as a Bearer token. It does not cover exclusions for all sibling tools, but it gives clear context for the most relevant alternative.

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