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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so the safety profile is covered. The description adds the default-to-OPEN filtering behavior and the registry framing, but says nothing about result size, pagination, or workspace/auth scoping beyond what the schema states. Adequate but not rich.

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?

Two sentences, front-loaded with what the tool lists before moving to guidance. The colloquial aside ('This is where you keep your head') is colorful rather than wasteful, though it dilutes precision slightly.

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 a four-optional-parameter read tool with no output schema and full schema coverage, the description covers what it returns (open questions/gaps), the default filter, and the workflow it supports. Nothing critical is missing, though return shape is left implicit.

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 100%, so all four parameters (status, subjectId, workspace, subjectType) are already documented, including the OPEN default and the workspace-token rules. The description only echoes the default status behavior, adding nothing new. Baseline 3 is correct.

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?

Specific verb+resource: 'Lists the workspace's open questions — the gap registry: what the map doesn't know yet.' The metaphor is anchored to a concrete concept (gaps), so an agent knows what it retrieves. It does not explicitly distinguish itself from siblings compass_gaps_create/resolve/update, so it stops short of a 5.

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?

Gives real usage context: 'check it before asking the user something you may already have flagged, and compose interview briefs from a subject's open questions.' That tells the agent when to reach for it. It does not name an alternative tool or state exclusions, so no 5.

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