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

Annotations already establish readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine domain behavior: commission is per standard lot in the quote currency, and commission-in-pips is position-size invariant by construction. It does not discuss edge cases such as zero commission or non-standard lot conventions.

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 sentences, front-loaded with the core purpose, then the commission/scale invariant, then the return key list. Dense but each sentence carries meaning; the mid-sentence derivation of size-independence is slightly verbose but earns its place by preventing unit errors.

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 no output schema and five parameters, the description compensates fully: it enumerates the returned keys (pipSize, commissionPips, totalCostPips, breakevenPrice) and explains the unit conventions of the inputs. An agent has everything needed to call and interpret the tool.

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 the baseline is 3. The description goes beyond the schema by explaining the semantics of commissionPerLotRoundTrip (per standard lot, in quote currency, default 0 pure-spread model) and why its pip conversion is size-independent, which helps an agent reason about the units rather than just passing numbers.

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+resource: computing a forex position's breakeven price inclusive of spread and round-trip commission, in both pips and price. This is well differentiated from generic breakeven siblings by the 'forex' + 'commission' scope, but it never names the closest siblings (run_breakeven_planning, run_funding_breakeven) it could be confused with.

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?

Provides an explicit trigger phrase: 'Use when user asks "where's my true breakeven after spread and commission?"', which gives a clear context for invocation. It stops short of stating when NOT to use it or which alternative handles the simpler spread-only case, so routing among the many breakeven/pnl siblings is left to inference.

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