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

Annotations already declare a non-read-only, non-destructive, non-idempotent write; the description adds substance on top of them: the single-bid limit is a hard constraint an agent can only learn here, and the payouts/delivery-endpoint conditions explain why a bid may be accepted but not paid. It still says nothing about what happens after submission (acceptance, rejection, editability of price), which caps it at 4.

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?

Three short sentences, front-loaded with the action and its payload, then constraints, then the auth requirement. Every clause carries information and nothing is padded.

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 write tool with full schema coverage, annotations and no output schema, the description covers the prerequisites an agent needs before calling: key, payouts, delivery endpoint, single-bid limit. The remaining gap is outcome information — whether a submitted bid is editable or withdrawable — which is a modest omission rather than a blocking one.

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 all four parameters, units (Rappen, hours) and the tender_id provenance are already documented in structured fields. The description's parenthetical that the note doubles as the answer to a question largely restates the schema's own wording, so it adds little beyond the baseline 3.

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 clause names a specific verb and resource ("Bid on a tender") and enumerates the payload it carries (price, delivery time, note), so an agent knows exactly what act is being performed. It does not name a sibling, and the boundary against close candidates like second_proposal or propose must be inferred, which keeps it below a 5.

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?

It gives real preconditions rather than mere context: one bid per tender, payouts must be connected, a delivery endpoint must exist, and a key is required. It stops short of routing advice — nothing says where to go if you have already bid (second_proposal) or how to withdraw — so it is clear but not complete on alternatives.

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