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

The description discloses the stateful behavior of the tool: 'The first run on a new filter creates the baseline and says so,' which is critical for understanding its operation. It also adds pricing context ($0.05/call, x402 on base) that annotations do not cover. Annotations indicate non-read-only and non-idempotent behavior, and the description complements this without contradiction.

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 composed of only two sentences, front-loading the core purpose and adding baseline and cost details efficiently. Every sentence contributes value, and there is no redundant or filler content.

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?

The tool has a nested filter object and no output schema, but the description explains the core behavioral contract: it returns only new listings since the previous check and handles baseline creation. It does not detail the output structure or how to reset the baseline, but the schema's baseline_key description addresses watch management, making it adequate for moderate complexity.

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?

All four parameters (filter, portal, max_items, baseline_key) have detailed descriptions in the input schema, achieving 100% schema coverage. The tool description does not add additional parameter-level meaning beyond what the schema already provides, so it relies on the schema for parameter understanding.

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 watches a property portal for a saved filter and returns only listings that appeared since the previous check, giving it a specific verb and resource. This distinguishes it from sibling portal-specific scrapers (e.g., krisha-kz, rightmove-london) by emphasizing its monitoring/alert role. The first-run baseline behavior further clarifies its purpose.

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 implies periodic monitoring ('since the previous check') and mentions the first run creates a baseline, but it does not explicitly state when to use this tool over the underlying portal scrapers or other alert tools. No alternatives or exclusions are provided, so usage guidance remains implicit rather than explicit.

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