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

Beyond the annotations, the description discloses that the position is an opaque string stored verbatim and never interpreted, that the tool never charges, and how authentication can be done. These are useful behavioral details not present in the schema or annotations. There is no contradiction with 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?

The opening sentence is front-loaded and useful, and the auth/route notes are practical. However, FREE appears twice with effectively the same claim, which is redundant and slightly weakens the structure.

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 tool with two required parameters, full schema coverage, and idempotentHint, the description covers the core behavior, storage semantics, cost, authentication, and HTTP route. It does not describe return values or overwriting behavior, but no output schema exists and the idempotentHint makes that less critical.

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 five parameters. The description adds a little context for position (stored verbatim, never interpreted) and auth guidance, but it does not meaningfully expand parameter semantics beyond what the schema provides.

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 states a specific action — record how far you got through a stream, feed, or table — and a concrete outcome: the next invocation knows where to start. It is not a tautology, but it does not explicitly contrast with sibling tools such as watermark_get or checkpoint_put, so differentiation relies mostly on the tool name.

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 a clear use case: persist a resume position so future invocations can continue from that point. It also covers the authentication prerequisite. However, it does not name alternatives or say when not to use this tool, so it stops short of full routing guidance.

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