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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered; the description adds genuinely new operational context — a $0.02 cost, an API-key requirement, and the instruction to disambiguate matches by date before acting. It doesn't cover result pagination or what happens with zero matches, but the cost/auth disclosure is real value beyond the structured fields.

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 sentences, front-loaded with the core purpose, then the operational constraints in a compact parenthetical. Dense but not bloated; the capitalized EXISTING efficiently carries emphasis that would otherwise need another sentence.

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 only two required parameters, full schema coverage, and an output schema covering return values, the description supplies the remaining agent-critical facts: cost, auth, and how to resolve ambiguous matches. Nothing essential for a correct call is missing.

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 schema already documents both parameters, including 'literal name' and the entity_type enum. The description restates the entity kinds and mentions dates for disambiguating meals/events, but that is a return-value nuance rather than added parameter meaning, so 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 (find) and resource (existing food entry, private event, inventory item, contact) and emphasizes EXISTING, which separates it from the create/attach siblings. The clause 'Returns stable entity_id for image attachment' tells the agent what the result is for, so it can be distinguished from find_identity_candidates without opening either schema.

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?

'Find an EXISTING ... never create a duplicate just to save an image' gives a clear use condition plus an explicit prohibition, and 'Ask which match' prescribes behavior when results are ambiguous. It stops short of naming a specific alternative tool to call instead, but the when-to-use context is clear.

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