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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered structurally. The description adds genuinely new information with the 'cost: 2 credits' note, but it says nothing about text truncation (relevant given the maxChars parameter) or the shape of the returned text.

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 front-loaded sentence identifies what is returned, from where, and at what cost, with no wasted words. The parenthetical cost is well placed at the end.

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 three-parameter fetch tool with no output schema and full annotation coverage, the description covers the essentials but omits two things an agent would want: expected URL format (all parameters are technically optional) and whether output is truncated by maxChars.

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 the baseline is 3. The description does add meaning by implying 'section' narrows the fetch to a single provision of the Act, but it says nothing about maxChars or whether url must be a full legislation.gov.uk address versus an identifier.

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 names a specific resource ('Text of an Act or instrument, or one section') and its source ('from its legislation.gov.uk URL'), which an agent can distinguish from the sibling legislation_search tool. It stops short of explicitly naming that sibling or stating the division of labor between search and fetch.

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?

Usage is only implied: the phrase 'from its legislation.gov.uk URL' signals that this is a follow-up fetch after locating a URL, presumably via legislation_search, but that prerequisite is never stated. There are no explicit when-not conditions or alternatives named.

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