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 genuinely non-derivable behavior: results are ranked by fit and explicitly unsponsored ('no product pays for its place'), and it discloses the per-product payload (price, why it fits, watch-outs, HMRC listing, vendor site, Landlord Lookout link). Minor gap: no mention of pagination beyond the limit cap.

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 sentences, front-loaded with purpose and ordering, then filters, then the return payload. Dense but every clause carries information; the long filter enumeration is slightly list-like but matches the ten-parameter surface it must cover.

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?

With ten optional parameters, no output schema and a non-obvious ranking behavior, the description supplies the missing pieces: fit ordering, sponsor-neutrality, and the shape of each returned product record. Nothing an agent needs in order to call and interpret this tool is absent.

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 every parameter is already documented at a high standard, including enum semantics for records and other_income. The description largely restates the same filter list and adds no syntax or edge-case detail beyond the schema (it does echo the bridging-software nuance, but that is already in the schema). Baseline 3 applies.

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?

Opens with a specific verb and resource ('Lists software from HMRC's list of Making Tax Digital for Income Tax software') plus the ordering rule ('in fit order'), which cleanly separates it from the sibling get_mtd_software_product (single product) and check_mtd. An agent knows exactly what comes back and in what order without opening the schema.

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?

The description enumerates the filters that drive selection (income types, records, free plan, properties, filing, VAT, Welsh, platforms), which implies the conditions under which the tool is the right pick. However, it never names an alternative tool or states when NOT to use it (e.g. when a specific product is already known, use get_mtd_software_product), leaving routing to inference.

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