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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds a genuinely non-obvious behavioral trait the annotations cannot convey: returned amounts carry no currency and require a separate settings lookup to interpret.

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 tight sentences, front-loaded with the core action and followed immediately by the one caveat an agent must know before reporting numbers. No filler or restated title material.

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 single-record getter with full annotation coverage there is no output schema, so return-shape explanation is not required. The currency caveat covers the highest-risk ambiguity; only the set of returned fields is left unspecified, which is acceptable for this tool class.

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% and the single 'id' parameter is already documented as a UUID-format budget item ID. The description's 'by ID' adds cardinality context but no format, validation, or lookup-hint detail beyond the schema, so the baseline 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?

States a specific verb and resource ('Get a single project budget item') plus the retrieval key ('by ID'), which implicitly distinguishes it from the sibling list_project_budget_items. It stops short of naming that sibling explicitly, so an agent must infer the single-vs-list split.

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?

Gives a concrete usage instruction for the data it returns: amounts are unitless, so call get_organization_settings for currency_code before stating a figure. That is actionable context, though it offers no guidance on when to prefer this tool over list_project_budget_items.

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