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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false; the description reinforces this by noting that re-saving changes nothing and nothing is removed, which is useful for an agent worried about duplicates. The addition of "Free" is genuine cost transparency not captured in annotations. It does not describe what is returned (e.g., a new list id), which is a minor 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?

Four short sentences, front-loaded with the action and destination, followed by trigger conditions, input shape, idempotency note, and cost. Every sentence carries information and the one-word "Free." is maximally efficient.

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 3-parameter mutation with no output schema, the description covers destination, trigger, inputs, and idempotency. The remaining gap is the absence of any statement about what the call returns (e.g., the created list's id), which an agent would otherwise have to discover empirically.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning by framing leadListId and newListName as alternatives ("either the id of an existing list or a name for a new list") — a relationship the schema itself never states. It also confirms buildingIds is the primary input.

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 (saves), resource (buildings), and destination (a lead list in the user's baseray workspace), which cleanly separates it from siblings like list_lead_lists, find_buildings, or get_building. An agent can identify the operation without opening the schema.

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?

"Use when the user asks to save, add or export buildings to a list" gives explicit trigger conditions, and the description clarifies the two routing modes (existing list id vs. new list name). It stops short of naming an alternative tool or stating when not to use it (e.g., vs. list_lead_lists), so it falls just under full marks.

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