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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the operation is a partial replace that leaves other configured modes intact. It does not, however, describe validation failures, permission needs, or what happens when a mode conflicts with existing session data.

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?

Two sentences, front-loaded with the core action and the mode enumeration, followed by the replace semantics that change how an agent sequences calls. No filler or redundant restatement.

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?

An output schema exists, so return values need not be explained, and the mode/replace model is well conveyed. The fatal gap is that a zero-parameter schema cannot support the kind-based invocation the description describes, leaving the agent without a usable contract for actually making the call.

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 declares zero properties, yet the description tells the agent to make calls 'with different kind values' and refers to 'the submitted mode' — input the schema never defines. With 0 params the baseline would be 4, but referencing an undeclared kind argument actively misleads an agent about what it must pass, so this is penalized.

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: configure one session-timing mode (fixed dates, recurring cadence, or just-in-time interval) for a webinar. The enumerated modes make the scope concrete and distinguish it from sibling updaters like update_core_details or update_replay_defaults, though no sibling is named explicitly.

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 clear invocation guidance: one call per mode, and multiple modes coexist because each call replaces only the submitted mode. What's missing is when to prefer this over the schedule-related sibling (clone_with_new_schedule) or any prerequisite that the webinar must already exist.

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