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

Beyond annotations, it discloses the failure mode ('build simulates CapabilityDenied'), the unsigned/local-signing boundary, the paid nature of the builder, and the expected return format. The description aligns with readOnlyHint=false, idempotentHint=false, and destructiveHint=false 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 front-loaded with the core purpose and prerequisites, followed by clearly labeled execution guidance. The only flaw is that the 'SAP MCP execution guidance' block is duplicated nearly verbatim in the input schema description, adding redundancy.

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 description covers what the tool does, its prerequisites, the activation fallback, failure behavior, pricing/routing, signer boundary, and return value. With an output schema present, nothing essential is missing for an agent to invoke this tool correctly.

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 description coverage is 100%, so the schema fully documents authority, amountUsdc, traderPdaIndex, and traderSubaccountIndex. The description adds context about USDC deposit semantics but does not meaningfully explain parameters beyond what the schema already states.

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: 'Build an unsigned USDC deposit transaction into a Phoenix trader account.' It also identifies the return value ('transactionBase64 for browser approval'), clearly distinguishing this builder from the many other sap_phoenix_build_* siblings.

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 explicit preconditions: check sap_phoenix_get_trader_state first and run the activation flow if the trader is frozen or depositCollateral.immediate is false. It also names the paid routing alternatives (sap_estimate_tool_cost, sap_payments_call_paid_tool) and tells the agent to finalize locally when signing is required.

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