Subscription plans

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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the description focuses on what annotations cannot express: prices are pre-VAT toman amounts, and the distinction between list price, new-user price, and the auto-renewing monthly plan. It also discloses a real data-provenance limitation (Filimo pricing absent from the JSON API), which prevents a wasteful call.

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?

Front-loaded with the purpose and the usage trigger, with field definitions in a compact second block. The only waste is the Filimo caveat appearing twice — once as a parenthetical and again at the end with the URL — which could have been a single statement.

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 no-parameter, read-only lookup with no output schema, the description covers everything an agent needs: when to call it, what the returned fields mean, currency/tax basis, and the one case where data is unavailable. Nothing material is left to inference.

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?

There are zero input parameters, so the baseline is 4. The description instead spends its effort defining the returned price fields (price, price_new_user, auto_renew), which is valuable given no output schema exists, though it does not describe ordering of plans or count of plans returned.

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?

Opens with a specific verb+resource ("Show Namava's public subscription plans and prices") and immediately delimits scope with the parenthetical that Filimo prices are not in its JSON API. An agent can distinguish this from sibling tools like vod_title or vod_search without opening the schema, since none of them concern pricing.

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 an explicit trigger phrase ("Use for 'how much is a Namava subscription'") and simultaneously states when-not/where-else: Filimo prices are only on the payment page, with the URL supplied. The routing decision is fully determined by the description.

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