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

Annotations declare destructiveHint=false and openWorldHint=false, but no readOnlyHint, so the agent is not told outright that this is a mutating operation. The description does add real behavioral value by disclosing the consequence — the held number becomes purchasable by others — which is the key effect of the call. It stops short of covering what happens if no hold exists on the number, or whether the release is reversible.

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?

A single short sentence with the action and its consequence front-loaded and no filler. Nothing could be removed without losing meaning.

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 tool with a fully documented schema, no output schema, and annotation coverage of safety hints, the description covers what the call does and its effect on the number pool. It is only slightly short of complete because it omits the precondition that the workspace must currently hold the number and any error/disclosure behavior.

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%, including the note that inventory_id comes from desk_search_numbers, so the schema already does the heavy lifting. The description only gestures at the parameter as 'a hold... on a number' and adds no syntax or sourcing detail beyond the schema, making the baseline 3 correct.

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 gives a specific verb ('gives back') and resource ('a hold the workspace has on a number'), plus the downstream effect ('so others can buy it'). It is clearly distinct from desk_hold_number conceptually, though it never names that sibling or release_number explicitly, so the differentiation is inferred rather than stated.

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?

There is no explicit when-to-use guidance: nothing says this should be called after desk_hold_number, what state the number must be in, or how it differs from release_number/desk_claim_number. The agent can infer the scenario from the sentence, but no prerequisites or alternatives are offered.

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