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

Annotations already declare non-read-only, idempotent, non-destructive, and closed-world, so the bar is lower, yet the description still adds real context: tracking runs daily, and re-adding an already-tracked app merges countries instead of failing. It does not mention validation of the app_id, per-account limits, or failure behavior, keeping it short of a 5.

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, front-loaded with the action and outcome, with the edge case (already tracked) stated second. No filler or repetition of the title.

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 two-parameter, closed-world mutation with no output schema, the description covers purpose, scope, and the idempotent-merge edge case. It is slightly thin on what the caller gets back and on prerequisites (e.g., needing a resolvable App Store id), but nothing essential 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 coverage is 100%, so baseline would be 3, but the description adds merge semantics for countries (added to an existing tracked app rather than replacing) and clarifies the countries scope of tracking. It does not add anything about app_id formats beyond what the schema already documents.

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 states a specific verb and resource ("Adds an iOS app to the user's Fledly account") and names the concrete outcome (daily rank and metadata tracking in given countries). This clearly separates it from siblings like get_app, get_my_apps, and track_competitor without needing to open any 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?

Usage is implied rather than stated: an agent can infer this is the tool for starting tracking, but there is no explicit guidance on when to prefer it over search_app_store/get_app to resolve an app_id first, nor any exclusion conditions. The one useful behavioral rule given is the already-tracked case, which is arguably behavior rather than usage guidance.

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