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

Goes beyond the annotations by disclosing the downstream effect that the person will be emailed/texted about notices and may receive a confirmation, plus a consent constraint. Annotations already flag destructive/non-idempotent, but the description never says what happens when the address is already subscribed (error vs. duplicate), leaving a real gap.

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-loads the operation type and the key constraint in two short sentences. Every clause — consent, no bulk import, confirmation send, endpoint reference — carries information an agent needs.

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 5-parameter write tool with no output schema, the description covers purpose, consent, side effects and the endpoint. It stops short on duplicate-subscriber behavior and on what the call returns, which an agent would need to interpret the result.

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 schema already explains email, phone_number, page_id, confirm and component_ids. The description only adds the 'email and/or phone number' framing and says nothing about component_ids scoping, so it adds little beyond structured data.

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 and resource ('add ONE subscriber ... to a status page') and scopes it against bulk import and, implicitly, against the sibling sorryapp_list_subscribers. The 'WRITE:' prefix plus the API endpoint make the operation unmistakable.

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 when-to-use rule ('Add only people who asked to be notified') and an explicit exclusion ('No bulk import'). It does not route to alternatives such as checking sorryapp_get_subscriber / sorryapp_list_subscribers first, so it falls just short of a 5.

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