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

With no annotations, the description must carry the burden. It discloses the data's temporal nature and the house-only limitation, and adds a cost note (30¢ per call), which is useful. However, it does not mention behavior for invalid inputs, empty results for units, or whether authentication is required. The information is decent but not comprehensive.

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 description is two sentences plus a cost line. It is front-loaded with the core purpose and constraint, with no wasted words. The structure is easy to scan and understand quickly.

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?

Given there is an output schema (so return values are covered), the description still fails to explain the single input parameter and does not detail what exactly happens for units (e.g., error vs empty). The house-only rule is stated, but the input semantics are missing, making the tool insufficiently documented for a one-parameter call.

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 0%, and the description does not explain what 'gnaf_id' is or how it should be formatted. The agent is left guessing whether it's the G-NAF identifier, a property ID, or something else. The description adds no semantics beyond the bare parameter name, so this is a weak spot.

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 clearly states the tool's function: 'Modelled property value over time' with specific frequency details (monthly for last year, annual before that) and restricts to houses only. This distinguishes it from siblings like sales history or current valuation tools.

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?

The description gives a concrete exclusion ('Houses only — units have no series') which tells the agent when NOT to use this tool, but it does not name alternatives or explicitly state when to prefer this over other valuation tools. It lacks a clear 'use this when' or 'use X instead' guidance.

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