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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does this exceptionally well by revealing that JWT expiry is not enforced, tokenRevision is incremented, previous session JWTs become invalid, server-side expiry is extended by 1 hour, and email backfill is best-effort. These are exactly the non-obvious side effects an agent needs to know.

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 dense but front-loaded with the core behavior, then covers side effects, return value, and invocation details. Almost every sentence adds necessary information, though the final note about preferring stable connection config is slightly tangential and could be integrated more cleanly.

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 complex tool with no annotations and no output schema, this description is highly complete. It covers authentication, token parsing and validation rules, side effects, return values, expiry extension, URL encoding, and required auth fields. An agent has enough context to invoke this tool correctly and anticipate its effects.

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?

Despite the schema coverage signal showing 0%, the description meaningfully explains the critical parameters: sessionToken is a potentially expired internal JWT in the path and must be URL-encoded, auth.firebaseToken is required and sent as a Bearer token. It also adds practical guidance about connection.workspaceName and connection.appId, going well beyond the bare schema.

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 a specific action: renew a session JWT by verifying a Firebase token, invalidating prior session tokens, and returning a new token. It explicitly differentiates what this tool does from sibling tools like post_sessions_revoke and post_sessions_revoke_session_id by focusing on token renewal rather than revocation.

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 explains the exact use case: replacing an expired session token while still validating the Firebase identity and session ownership. It also specifies the URL form and URL-encoding requirement, but it does not explicitly mention alternatives or when not to use this tool, so it stops short of full exclusion guidance.

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