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

This is an annotation contradiction. The annotations declare readOnlyHint=true, implying the tool makes no state changes, but the description says it 'Declines the offer' and 'the offerer is notified' – both non-read-only mutations. The description also fails to correct the misleading annotation, making the behavioral contract inconsistent.

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 short and front-loaded with the core purpose. The parenthetical repeat 'Declines the offer' is slightly redundant with the initial phrase, costing a small amount of efficiency, but overall it remains compact and readable.

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 low-complexity tool with schema-covered parameters, the description explains key side effects and error cases. However, the contradiction with the readOnlyHint annotation leaves the agent with conflicting signals about whether this is a safe read operation, and the description does not explicitly state that it is a mutating action. That gap is significant enough to keep the tool from being contextually complete.

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 schema already describes both parameters (trade_id and session_id) with 100% coverage. The description adds no extra parameter-level detail, such as how trade_id is obtained, so the baseline of 3 applies.

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 opens with the clear verb-plus-resource phrase 'Decline a trade offer', which immediately tells an agent what the tool does. It is succinct and distinct from most siblings, though it does not explicitly differentiate from the similarly-named trade_cancel or trade_accept.

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 no guidance on when to use trade_decline versus trade_cancel or trade_accept. It lists failure modes but does not state the selection conditions (e.g., 'use this for offers you received; use trade_cancel for offers you made'), so an agent must infer the intended use case from the name alone.

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