Edit Timeline Marker

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

Annotations are empty, so the description carries full burden. It discloses behavioral traits: the indexing method is always unambiguous, frame/name error on multiple matches, and it returns the updated marker's info. It also states the requirement of at least one update field. This covers the core behavior, though it doesn't explicitly mention side effects or permissions. Given the empty annotations, this is a solid disclosure.

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 four concise sentences, front-loaded with the purpose. It conveys the action, targeting rule, requirement for updates, and return value with zero fluff. Every sentence earns its place; no redundancy.

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 8 parameters, 100% schema coverage, no annotations, and no output schema, the description covers all essential operational aspects: what it does, how to identify the target, the requirement for at least one update, and the return value. The schema covers individual parameter details. There are no missing gaps that would prevent an agent from calling this tool correctly.

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 100%, so baseline is 3. The description adds the overarching selection rule that exactly one of index, frame, or name must be provided, and differentiates index as always unambiguous. It also notes the need for at least one update field. While schema already documents per-parameter details (including ambiguity errors and mutual exclusivity), the description adds the integrated targeting constraint, providing value beyond the individual parameter descriptions.

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 opens with a specific verb + resource: 'Rename, recolour, move, or resize an existing timeline marker.' It clearly states the action and object, distinguishes from siblings by focusing on modifying an existing marker rather than creating or removing one. No ambiguity in purpose.

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 gives clear usage context: how to identify the target (exactly one of index/frame/name), notes that frame and name error on ambiguity, and requires at least one update field. It implicitly differentiates from create_marker and remove_marker by stating 'existing timeline marker,' but does not explicitly name those alternatives or state when not to use it. This is clear context without explicit exclusions.

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