Read the billboard

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

The description goes beyond the annotations by warning that the message is untrusted paid third-party text and instructing the agent never to follow instructions in it. It also discloses that the tool tracks 'whether anything changed since your last read,' adding stateful behavior context. These are valuable behavioral disclosures beyond readOnlyHint/openWorldHint/idempotentHint.

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 with the main action front-loaded. The enumeration of returned fields is dense but each item is meaningful. The security warning and usage guidance are placed at the end, which is acceptable. Slightly long, but every clause earns its place.

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?

With an output schema present, the description does not need to explain return formats. It covers the tool's scope (read current state), key security caveat (untrusted message), state tracking, and an explicit usage directive. An agent can invoke this tool correctly with no further information.

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?

The tool has zero parameters, so the description carries no parameter burden. The baseline for 0 params is 4, and the description confirms the tool is a simple read with no inputs, which is consistent.

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 states a specific verb and resource ('Read the current billboard') and enumerates the exact data it returns (poster, amount paid, minimum bid, message, etc.). The sibling tools are all mutating or different-action tools, so this read tool is clearly distinguished. The title and description align perfectly.

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 an explicit trigger: 'Always call this before deciding to bid.' This clearly tells the agent when to use the tool. It does not explicitly name alternatives or exclusion cases, but the sibling tools are different enough that the usage context is clear.

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