marker_upsert

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

There are no annotations, so the description carries the full behavioral burden. It does well by disclosing idempotency on payload.id, the create-or-replace semantics, and the special behavior when payload is omitted. It does not mention permission requirements or exact side effects of replacement, but it gives meaningful behavioral context beyond the tool name.

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 description is compact and organized into a concise summary, a field listing, and a usage hint. The 'If payload is omitted' sentence is somewhat confusingly worded, but overall the description earns its length and is not bloated.

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?

Given the extremely sparse input schema, the description provides essential context about the marker object shape, idempotency, and when to prefer an alternative. The presence of an output schema reduces the need to explain return values. The main gap is the slightly unclear payload-omitted behavior, but the overall context is adequate for an agent to invoke the tool with reasonable confidence.

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 parameter semantics. It does so effectively by enumerating the marker object fields: type/name, frame, optional scope with explicit enum values, color, note, duration, unique_id, media_id, and payload structure. This is substantially more informative than the bare schema, which only declares an array of arbitrary objects.

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 clear action ('Create or replace typed markers') and identifies the resource type, along with the idempotency key ('payload.id'). It does not explicitly differentiate itself from sibling tools like markers_query or markers_clear, though it does mention markers_from_metadata as a preferred alternative for a specific use case.

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?

The description provides a concrete routing hint: 'Prefer markers_from_metadata for mapping.' This tells the agent when an alternative is better suited. However, it does not explicitly state when marker_upsert should be used versus the other marker-related siblings, leaving some inference required.

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