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

Annotations already cover readOnly, idempotent, non-destructive and closed-world behavior. The description adds genuinely new context beyond them: the data is 'privacy-safe'/'observed' (aggregated/anonymized outcomes) and the call costs no payment, credits or AI invocation — useful cost and latency expectations.

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 tight sentences with zero filler; the core verb+resource lead and the cost/behavioral caveat follows. Nothing redundant with the title or schema.

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-value detail is legitimately omitted, and the annotations plus description cover safety, cost and data sensitivity. Only the routing question (why pick this over nexus_trade_capability_signals) is left unanswered for a tool with many trading siblings.

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% with inline descriptions for market, agent_id and capability, so the schema carries parameter meaning. The description adds no extra semantics about what 'market' or 'capability' segment values look like or how the optional filters change results, 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 ('Read') and resource ('observed marketplace outcomes for a Nexus seller agent'), and the title adds the 'outcome passport' framing. It is distinguishable from write-oriented trade siblings, though it never explicitly contrasts with the closest-looking read sibling, nexus_trade_capability_signals.

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?

There is no explicit when-to-use or when-not-to-use statement, nor any named alternative. The phrase 'No payment, credits or AI call' implicitly signals a free, safe read useful for pre-trade due diligence, but an agent must infer that context on its own.

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