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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the agent knows this is a non-idempotent mutation. The description adds nothing beyond that: it does not disclose what state is changed, whether an advance is irreversible, what happens on an invalid or expired session, or what errors to expect. For a stateful non-idempotent mutation with no output schema, this is a serious disclosure gap.

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?

It is short, but this is under-specification rather than conciseness: nine words, of which four are a bracketed identity tag and two restate the title. There is no front-loaded statement of effect or return, so the brevity costs the agent all actionable information.

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 non-idempotent, state-mutating session tool with zero schema description coverage and no output schema, the description supplies nothing an agent needs: no effect, no precondition, no result. Every behavioral question is left unanswered.

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 0%, so the description must carry the load, and it says nothing about session_id. The only aid is the schema's "sess-001" example, which conveys format but not provenance, validity rules, or whether the session must already exist. The parameter name is self-explanatory enough to avoid a 1.

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?

"advance session" restates the tool name (Ratchet Advance) and adds no resource detail: it never says what a session is, what "advancing" does, or what state transition occurs. The "[identity] RatchetGate" tag hints at a domain but is not a purpose statement. An agent cannot distinguish this from ratchet_register or any other session-mutating sibling on the basis of this text.

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?

There is no when-to-use guidance, no preconditions, and no mention of the obvious alternative ratchet_register despite it being in the sibling list. Nothing tells the agent whether a session must first be registered, whether advancing is repeatable, or what triggers a call.

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