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

Annotations already declare destructiveHint=true and idempotentHint=false, so the mutation/non-idempotent nature is known. The description adds real value beyond that: it warns that future occurrences publish automatically and urges confirming replacement values, plus the two-minute startsAt lead-time rule. This is solid behavioral context, though it does not clarify partial-vs-full replacement semantics.

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, no padding, and the core action is front-loaded before the constraints. Every clause (mutable facets, startsAt rule, auto-publish warning) earns its place.

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 destructive update tool with a rich nested schema and no output schema, the description covers the essential behaviors: what is replaced, the timing constraint, and the auto-publish consequence. The main remaining gap is not distinguishing partial updates from full replacement, but the coverage is otherwise sufficient.

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 low (36%), so the description carries some burden. It clarifies only the startsAt constraint (at least two minutes in the future); the other parameters, including the recurrence fields (endType, occurrenceCount, weekdays, interval), get no explanatory help beyond the schema. The nested platformOptions object is self-documented, which keeps this at baseline.

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 names a specific verb ('Replace') and enumerates the mutable facets of a recurring series (next occurrence, recurrence rules, content, media, platform options). This clearly distinguishes it from create_recurring_post and manage-only siblings like list_recurring_posts, though it does not name those siblings 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?

It scopes the target ('active or paused recurring series') and gives a precondition for startsAt, which is useful context. However it never states when to prefer this over alternatives such as reschedule_post, so usage is only implied rather than guided.

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