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

Goes well beyond the annotations: it discloses that the enquiry is sent in the sender's name, requires name/e-mail/message with phone optional, that agency-website listings are forwarded to the agency, and the key flow difference — signed-in users get immediate send, everyone else receives a confirmation-link e-mail. These are non-obvious behaviors an agent must plan around.

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?

Front-loaded trigger clause followed by requirements, listing scope, and send flow in a compact paragraph. The parenthetical stack of translation keywords is clutter for a purely human reader, but it aids intent matching and does not obscure the core 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?

For a six-parameter, non-idempotent, open-world write with no output schema, the description covers requirements, scope and the post-send flow. It omits what the agent should do with listing_id selection and the language parameter, and says nothing about failure handling.

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 only 33%, and the description compensates for the core fields by noting name, e-mail and message are needed and phone is optional. However, listing_id and the language enum are never mentioned in the description, so it only partially covers the gap.

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 ('sends the enquiry in their name' to 'the provider of a listing'), and the multilingual trigger phrases plus the two supported listing types make it distinguishable from siblings like book_viewing, owner_enquiry and apply_for_listing without opening a 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?

Explicit trigger: 'Use this when someone wants to contact the provider of a listing', with clear scope for Heimster listings and 'found:<id>' agency listings forwarded to the agency. It does not name an alternative tool or state when *not* to use it (e.g. vs owner_enquiry or book_viewing), so it stops just short of a 5.

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