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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint, so the safety profile needs no description. The description adds directionality and ID provenance but says nothing about result volume, pagination behavior for the limit parameter, or the shape of the returned list.

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 tight sentences, front-loaded with the reverse-lookup framing and the scope of the returned set. Every clause carries information; nothing is redundant.

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?

There is no output schema, so the description's statement of what gets returned (the list of covered entities) carries the burden and it does so adequately. For a two-parameter read tool with full annotations, this is nearly complete, with only result-volume behavior left unstated.

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 both parameters are already documented, setting a baseline of 3. The description goes beyond the schema by explaining where pharmacy_id values originate ('come from a covered entity's detail page'), which is genuinely useful caller guidance the schema lacks.

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 ('list every 340B covered entity') with an explicit directionality qualifier ('Reverse 340B lookup'), which distinguishes it from the forward search_340b sibling without naming it. An agent can infer the direction difference, but the sibling is not called out by name.

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 precondition ('given a contract-pharmacy ID') and motivating context ('reveals how concentrated the contract-pharmacy network is'). It does not state when-not to use it or name search_340b as the forward alternative, so alternatives are only implied.

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