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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description goes well beyond that, disclosing the shape of returned items: statusName vs statusCategory semantics, the legacy `status` lane key, the `experiment`/`ledgerEntryId` null-means-no-expectation rule, and `ledger.verdict` values after settlement. This is meaningful behavioral context that an agent would otherwise have to discover empirically.

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 text is information-dense but not front-loaded: the opening sentence describes the resource rather than stating what the tool does, so an agent scanning the first clause does not immediately learn the operation. Most sentences carry real payload, but the heavy backtick-heavy prose and lack of a clear action-first structure hurt scanability.

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?

With no output schema, the description carries the full burden of describing returns and does so well — item fields, status semantics, experiment/ledger linkage, optional scores and workflow anchor. It is nearly complete for a zero-required-param list tool, though it omits pagination, result limits/ordering, and default-scope behavior.

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 the baseline is 3. The description adds some value by explaining that `status` holds a 'lane key' and by mapping statusCategory stages (TRIAGE/BACKLOG/ACTIVE/DONE/CANCELED), but it does not clarify the relationship between the schema's lane enum values (NEW, QUALIFYING, EXPERIMENTING, SETTLED, REJECTED) and those categories, nor add format detail beyond the schema.

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 defines the returned resource ('the workspace's changes — fixes, chores, new steps, experiments') in rich detail, but never states the action itself — the fact that this enumerates opportunities is carried only by the name/title. It also does not differentiate this list operation from siblings such as compass_opportunities_propose or compass_opportunities_create. Purpose is inferable from the title but the description alone is vague about the verb.

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?

It gives concrete filtering guidance ('Filter by lane key in `status` or by workflowPageId') and points to a companion tool for status names ('compass_statuses_list has the status names'), which is genuinely useful routing. However there is no when-to-use versus when-not-to-use statement, no mention of what it excludes, and no indication of when a caller should prefer a different listing tool (e.g. compass_pages_list) instead.

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