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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the 'Read-only' clause is redundant. What the description adds beyond the structured data is genuinely useful: it discloses that the call is cheap, that it is a sensible first call, and that it returns null when no card exists yet — a non-obvious return behavior.

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?

Three tight clauses, front-loaded with the verb and resource definition, followed by cost/ordering guidance and the null-return caveat. No filler sentences and nothing repeated from the 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 structure need not be described, yet the description still flags the null case. With annotations covering the safety profile and full schema coverage on all three parameters, an agent has everything needed to call this correctly.

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%, and the schema already explains peer_id, workspace_id defaults, and the target_peer_id indirection in detail. The description adds no parameter-level semantics beyond that, 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 and resource ('Get the peer card') and immediately defines what the resource is: 'a short list of the most stable facts about a person (name, location, role, preferences).' That content definition cleanly separates it from siblings like search, list_conclusions, or get_session_context, none of which return a per-person fact card.

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?

'Cheap; a good first call' gives an explicit ordering heuristic for when to reach for this tool, which is real routing guidance. It stops short of naming alternatives or stating when not to use it (e.g., when you need richer context, use get_session_context), so it is clear but not exhaustive.

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