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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the concrete auth requirement ('Requires recipients:read in the connected organization') and the scoping qualifier 'authorized,' which tells the agent that permission failures are a real outcome. Return field list is largely redundant given an output schema exists.

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 verb, resource and key requirement, followed by permissions and exclusions — a sensible order. The enumerated return-field sentence partly duplicates the output schema and is the one element that does not fully earn its place.

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 read with an output schema and full annotations, the description covers purpose, required permission, and negative scope (no update, no generation, no delivery). Nothing an agent needs to call it correctly 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 0% and the two parameter names are ambiguous on their own, but the description disambiguates the critical one by clarifying that 'id' is the campaign id paired with recipient_id. It adds no format or constraint detail beyond that, and the UUID pattern lives only in the schema.

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 ('Read one authorized campaign recipient') plus the exact key pair required, which immediately separates it from the sibling list tool recipients_list. An agent knows this is a single-record fetch, not a query or enumeration.

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?

'Use it to inspect an existing contact' gives a clear usage context, and 'it does not update the recipient or perform generation or delivery' rules out the mutation and production paths. It stops short of naming recipients_list as the alternative for enumeration, so it is clear but not fully routing.

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