add_marker

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. While it mentions that the sequence need not be active, it does not disclose potential side effects, whether the marker replaces existing markers, what happens with invalid input, or whether the operation is undoable. For a mutating operation, this lack of behavioral context is a significant gap.

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 extremely concise, comprising two short sentences that convey the primary purpose and a key usage detail. There is zero wasted text, and the most important information (what the tool does) is presented first.

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?

The tool is a simple mutation with a well-documented schema (100% coverage), no output schema, and no nested objects. The description communicates the core operation and the non-active-sequence flexibility. However, for a mutating tool with no annotations, the lack of response/return value behavior and edge-case handling makes it slightly under-specified, though it remains adequate for a straightforward operation.

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?

The input schema has 100% description coverage, so the schema already documents all parameters thoroughly. The description adds no parameter-specific information beyond the schema. Per the rubric, with high schema coverage, a baseline of 3 is appropriate.

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 clearly states the tool's function: 'Adds a marker to the specified sequence for navigation or notes.' It uses a specific verb ('adds'), identifies the resource ('marker' and 'sequence'), and mentions the purpose ('for navigation or notes'). This distinguishes it from siblings like delete_marker, update_marker, list_markers, and add_marker_to_project_item, though it doesn't explicitly name these alternatives.

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 notes that 'The sequence does not have to be the active one,' which is a useful usage hint. However, it does not provide explicit guidance on when to use this tool versus alternatives like add_marker_to_project_item or set_sequence_markers, nor does it mention any prerequisites or restrictions beyond the sequence not needing to be active.

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