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

Annotations provide no behavioral hints (readOnly/other flags all false), so the description must carry the burden. It discloses authentication behavior (token or Bearer session) and the dynamic action dispatch behavior. However, it does not describe whether actions are destructive or what responses look like, leaving the agent to discover via the 'no action' call. It adds some context but is not fully transparent.

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?

The description is two sentences. The first sentence front-loads the core purpose and authentication guidance; the second explains the resource/action pattern and discovery. Every phrase earns its place – no fluff or repetition. It is concise yet informative.

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?

Given the tool is a generic dispatcher with 4 optional params and no output schema, the description adequately explains the interaction pattern (resource/action) and the discovery mechanism. It does not enumerate possible actions or responses, but that is intentionally deferred via the 'no action' call. For a routing tool with this complexity, the description is complete enough, though it could mention typical resources or examples.

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?

The schema already covers all parameters with descriptions (100% coverage), so baseline is 3. The description adds value by explaining the token variable (sk_... or Bearer header) and the action parameter's omit behavior ('call with no action to see what's available'), which enriches the schema's generic description. It also clarifies that 'params' is optional for action-specific arguments, though it doesn't detail those arguments.

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 clearly states the tool's purpose: 'Manage reader subscriptions and donations' – a specific verb (manage) with a clear resource domain. It distinguishes from siblings by focusing on subscriptions/donations, which is distinct from payments, reporting, etc. The additional usage pattern ('Pass resource and action') reinforces the purpose.

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 provides clear usage context: authentication requirements (API token or Bearer session) and explicitly instructs not to ask for a token when a session exists. It also indicates a discovery mechanism ('call with no action to see what's available'), implying the tool is to be used for subscription/donation actions. It lacks explicit exclusion of alternatives, but the context is strong enough for an agent to decide.

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