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

Annotations declare idempotentHint and destructiveHint=false, but the description adds context they cannot carry: the rental-module prerequisite, the per-connection write permission constraint, the duplicate-resolution behavior (a match on every given part is returned instead), and the shape of the reply. It also explicitly discloses that the returned record is the saved property with its organisation's name, which is valuable given there is no output schema.

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 purpose is front-loaded and every sentence carries information (prerequisites, duplicate check, owner sourcing, follow-up call). It is dense, though, with several long chained clauses, and a few statements restate schema content that the agent already receives.

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 5-parameter creation tool with no output schema, the description covers the full picture: prerequisites (module, permissions, org scoping), duplicate handling, owner sourcing and pre-creation of contacts, the return value, and the natural follow-up call. Nothing needed to invoke it correctly is missing.

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: it tells the agent to ask the person who owns the property and in what shares rather than defaulting, and that the ownership split drives income/expense reporting. The mechanics of shares (sum to 100, 2 decimal places) remain in the schema, so this is a 4 rather than a 5.

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 first sentence names a specific verb and resource ('Adds a rental property') and immediately scopes it by what the record contains: label, address, and owner shares. It is trivially distinguishable from sibling create_* tools (create_tenancy, create_contact) because it names them as separate steps rather than overlapping them.

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?

Explicit when-to-use and dependency routing: check list_properties first to avoid duplicates, source owners from list_contacts (contact type property-owner), use create_contact for a new owner, add tenancies afterwards with create_tenancy, and only use it where the rental module is enabled and the connection may write. Naming the alternative for each sub-task leaves nothing to inference.

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