Update Marker

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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false. The description adds non-obvious behavioral context about undo-boundary protection and the undoTracked:false flag, but expresses it in dense, opaque jargon (QE DOM, undoStackIndex) that is hard for an agent to act on.

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 is front-loaded in the first sentence, but the trailing experimental paragraph is dense and jargon-heavy, and the phrase 'at a time' is awkward. Adequately sized but the caveat is hard to parse.

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 needn't be explained, and annotations cover the safety profile. However, the description omits practical preconditions such as whether the marker must already exist at time_seconds or what happens on an invalid position.

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% and the schema itself documents all four parameters, including color indices. The description only restates the field names without adding syntax, format, or edge-case meaning beyond what the schema provides, so the baseline 3 applies.

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 (update), resource (sequence marker), and the editable fields (name, comments, color). This distinguishes it from add_marker/delete_marker siblings, though it never names those alternatives 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?

The description gives no when-to-use guidance and no alternatives or prerequisites. It only implies usage through the word 'update', leaving the agent to infer that this modifies existing markers rather than creating or removing them.

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