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

With no annotations, the description carries the full burden and does reasonably well: "List" signals a read-only enumeration, the return fields (name, aka, class, status, licensed alternative) are disclosed, and the UK scope plus legal-status categories define coverage. No pagination or empty-result behavior is mentioned, but the operation is simple enough that this is a minor 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?

Four short sentences, each doing work: scope, filtering, return shape, and an exclusion statement that prevents misuse. Purpose and constraint are front-loaded with zero filler.

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?

No output schema exists, and the description compensates by listing the returned fields. For a two-optional-parameter read tool, scope, filter options, return shape, and misuse guard together cover everything an agent needs to call it correctly.

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 50% and the status enum is already fully enumerated in the schema, so restating the four values adds little. The category parameter already has its own description with examples (WL, Longevity, Repair), and the description adds no further semantics such as matching rules or combined-filter behavior.

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?

"List the UK peptide/compound profiles with their UK legal status" gives a specific verb and resource, and the closing line "A legal-status index, not a dosing tool" scopes it against dosing-oriented siblings. It never names the nearest sibling (compounds_get), so the boundary with the detail lookup is only implied.

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?

"Filter by status or category" implies usage for narrowing results, and the exclusion of dosing use is stated. There is no explicit when-to-use vs. compounds_get (single record fetch) or compare_medicines, so the agent must infer the choice from names.

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