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

With annotations only declaring the safety profile (non-read-only, idempotent, non-destructive), the description supplies the economics the annotations cannot: editing is free, each scheduled render is charged at render time, an underfunded balance skips the run rather than failing or overdrawing, and the daily agent cap applies. That is exactly the non-obvious mutation behavior an agent needs before triggering a recurring spend.

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 purpose and partial-update rule are front-loaded in two short sentences, which is the right ordering. The billing/scheduling tail is one long semicolon-chained run-on that takes two passes to parse, so it is dense rather than wasteful.

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 an 11-parameter mutation with no output schema, the description covers optionality, cost, scheduling cadence and the daily cap, which is most of what's needed. Gaps remain on side conditions — e.g. whether setting autoPost flags requires connected accounts, or a minimum on scheduleIntervalDays beyond the schema.

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 coverage is only 45%, so the description carries real weight — it names 9 of the 11 parameters, including the terse autoPostTikTok/autoPostYouTube/scheduleIntervalDays fields the schema leaves bare, and clarifies optional-field semantics via "only the fields you pass change." It adds no format hints for scheduleIntervalDays or brief length, which keeps it off a 5.

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?

"Change a series" plus an explicit enumeration of the mutable fields (name, brief, schedule, auto-post flags, madeForKids, motionMixLevel) makes the verb+resource unambiguous and separable from create/pause/resume siblings. It stops short of naming those siblings as alternatives, but the resource scope is unmistakable.

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?

"Only the fields you pass change" is a genuinely useful partial-update rule, and it points at autoshort_get_limits for the spending cap. However, nothing says when to reach for this versus autoshort_create_series, autoshort_pause_series or autoshort_resume_series, so the choice among siblings is left to inference.

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