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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false. The description reinforces this with 'No money is moved' and adds that currencies are kept separate in the projection, which is genuinely useful output context. No contradiction, but no additional secrets about scope, data freshness, or permissions.

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?

Two short sentences, front-loaded with the scope and the read-only reassurance, with zero filler.

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 simple no-arg read with full annotation coverage, the description covers what matters most. However, with no output schema, it could say more about what the projection contains (time horizon, per-currency totals, invoice basis), leaving a real gap for interpreting results.

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 single 'input' parameter is an empty object with no fields, so there is effectively nothing to document. Baseline 4 applies for a no-meaningful-parameter tool; the description correctly implies no arguments are needed.

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 (read) and resource (saved-invoice cash-flow projection), plus a scope qualifier that currencies are kept separate. It is clearly distinguishable from siblings like get_spend_summary or get_budget_actuals, though it doesn't name an alternative to contrast against.

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?

'Read the saved-invoice cash-flow projection' implies a read context but gives no explicit when-to-use guidance, no exclusions, and no reference to the many plausible sibling tools for spend/budget views. An agent must infer selection criteria.

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