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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, and the description reinforces this with 'Changes nothing' while adding context the annotations cannot convey: the sign-in prerequisite, the free beta state, and that session must be passed on every call. It stops short of explaining return shape or the beta's end behavior, but it clears the bar raised by the 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?

Three tight sentences with the blocker (sign-in required) front-loaded, followed by what is read and where to go for mutations. The alternative-tool routing is repeated in the schema, so there is minor redundancy, but nothing is wasted.

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 read-only tool with no output schema, the description tells the agent what data comes back (status, plan and limits, keys by prefix) and the auth precondition, which is sufficient to invoke correctly. It could say more about what 'keys by prefix' actually returns, but nothing essential is missing.

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%, so the schema already documents all four parameters, establishing a baseline of 3. The description only reinforces two points (action='keys' and that tier is unnecessary during the beta), adding marginal meaning beyond the schema rather than new syntax or constraints.

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?

States a specific verb and resource ('Read the signed-in account') and enumerates the returned content: status, plan with limits, and keys when action='keys'. It also names the sibling tools that handle the mutating paths (revoke_api_key, request_deletion), so the agent can distinguish read vs. write without opening schemas.

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?

Gives an explicit prerequisite ('call connect(email) and connect_verify first... unless this connection is already signed in') and routes mutation intents to revoke_api_key and request_deletion. It does not address the overlap with the sibling whoami, which plausibly also reveals the signed-in identity, leaving one alternative ambiguous.

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