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

Annotations already declare readOnlyHint=false and destructiveHint=false, and the description adds the critical fact annotations cannot convey: this SPENDS the user's coins at expected_cost, and expected_cost is 'the number on the button the person pressed.' That cost/spend disclosure is exactly the behavioral context an agent needs before invoking. It stops short of covering funding rules or retry semantics, which only appear in the schema.

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, with the exclusion ('not for a conversation') and the cost warning front-loaded. The 'upscale from the app:' fragment is mild filler but the rest earns its place.

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?

An output schema exists, so return values need no explanation, and annotations carry the safety profile. The description supplies the two things structured fields cannot: the app-vs-conversation scoping and the coin-spend consequence. The estimate_upscale prerequisite is only implied via the schema, not the description, which is the one remaining gap.

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%, so every parameter is already documented, making 3 the baseline. The description adds a small gloss on expected_cost ('the number on the button') that slightly re-frames the schema's 'coins estimate_upscale answered,' but it contributes no new semantics for kind, model, funding, or idempotency_key.

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 (upscale) plus the scope that matters most: 'For the Veltake app's own screens only — not for a conversation.' That negative scope is what separates it from the sibling `upscale`. The opening fragment 'upscale from the app:' redundantly restates the name, but the intent is unambiguous.

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 clear selection condition — use only for the app's own screens, not a conversation — which implicitly routes the agent away from the conversation-oriented sibling. It never names that alternative (`upscale`) or the prerequisite quote tool (`estimate_upscale`) directly, so the guidance is clear but not fully explicit.

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