post_entry

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

With no annotations provided, the description carries the full burden and delivers substantial behavioral context. It discloses the balanced-entry invariant, the two-leg minimum, the reversal-not-edit rule, and the idempotent retry behavior (returning original entry with replayed=true). This is far more transparent than typical descriptions.

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 three sentences long, front-loaded with the primary purpose, then key constraints, then retry guidance. Every sentence provides unique value with no redundancy or fluff. The structure is logical and easy to parse.

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 tool with no output schema, the description covers the essential operational aspects: how to construct legs, the balancing invariant, idempotency behavior, and the correction policy. It could go slightly further by stating the normal success return value, but the mention of replayed=true on retries implicitly covers the response shape. Overall, it is complete enough for an agent to confidently invoke this 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?

The schema already describes all parameters with high coverage (75%+), so the baseline is 3. The description adds significant meaning beyond the schema by explaining the balancing requirement for legs, the correct use of idempotency_key on retries, and the distinction between direction and sign for amounts. This elevates the score above baseline.

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 'Post a balanced journal entry' – a specific verb and resource – and immediately states the core accounting constraint (debits equal credits across at least two legs). It further differentiates the tool by asserting it is 'the ONLY way to change a balance,' distinguishing it from sibling read/query tools and the allocate tool.

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 provides explicit guidance: this is the only way to change a balance, corrections must be made as reversal entries rather than edits, and retries should reuse the same idempotency_key. This informs the agent when to use the tool and how to handle failure/recovery scenarios, going beyond generic alternatives.

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