Export your subscriptions as OPML

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

While annotations already mark destructiveHint=true, the description goes further by specifying exactly what will happen: it 'needs confirm: true and will overwrite whatever is at the path.' This gives the agent the precise consequence of invoking the tool and the necessary guardrail, which is especially valuable for a file-writing operation.

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 sentences each earn their place: purpose, behavioral hazard/confirmation, and realistic use cases. The most important safety information is front-loaded after the purpose, and there is no filler or repetition of structured metadata.

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 three-parameter export tool, the description covers what it does, when to use it, what path is for, and the overwrite risk. It does not describe the tool's return value, but for a side-effect-focused file export this is a minor gap rather than a blocking one.

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 the baseline is 3, but the description adds meaningful context beyond the schema: it warns that confirm must be true and explains the overwrite risk, which the schema's optional confirm field alone does not convey. It also clarifies the path's purpose by mentioning OPML compatibility with podcast apps.

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?

The description uses a specific verb ('Write'), names the resource ('shows you follow'), and states the output format ('OPML file'), so an agent immediately knows what the tool does. It also explicitly distinguishes it from sibling tools by noting 'This is the one tool here that writes anything.' This is clear and not a tautology.

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?

The description gives concrete use cases: leaving Apple Podcasts and backing up a follow list that exists nowhere else. It also frames the tool as the only writer among the siblings, which helps an agent avoid selecting it for read-only tasks. It stops short of naming a particular alternative tool, so it is not a perfect 5.

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