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

Annotations declare idempotentHint=true and destructiveHint=false; the description's 'Merged onto the stored profile for the same website' explains what merge semantics actually mean, which is the non-obvious behavior here and is consistent with idempotency. It does not disclose failure modes, permissions, or whether the response echoes the merged profile.

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 short sentences: what it does, how it merges, and the integrity constraint. Front-loaded and free of 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?

With no output schema, the agent still doesn't learn what a call returns (confirmation, merged profile, error shape) or what happens for a new website with no existing profile. Everything else an agent needs to call it correctly — merge semantics, delta sending, no invented facts — is present.

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% but the single parameter is an open object with additionalProperties and no enumerated keys, so the schema alone conveys little. The description compensates by explaining that values merge onto the existing profile (delta semantics) and that 'website' names the product, plus a content constraint on which facts are legal.

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?

Specific verb ('Saves') plus resource ('product facts (product.json keys)') and destination ('to the dashboard'). It is clearly differentiated from the read-side sibling get_product_profile by the verb alone, though no sibling is named.

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?

'send only what changed' gives concrete delta-usage guidance that an agent would otherwise get wrong, and 'Only facts the user confirmed: never invent pricing, metrics or features' is an explicit constraint. It stops short of naming when to prefer an alternative path (e.g., get_product_profile first to inspect before merging).

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