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

Annotations only state the read-only/no-side-effect profile; the description adds genuinely non-obvious behavior: every figure carries legal basis, source tier and date, absence means UNVERIFIED rather than no route existing, and it frames output as information not legal advice. That provenance and absence-semantics disclosure materially changes how an agent should interpret results.

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?

Front-loaded with the resource and scope, then the three modes in a predictable order; the long parenthetical enumerations of relatives and costs are dense but informative rather than padding. Slightly over-packed for a single paragraph, but every clause carries routing or scope information.

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?

An output schema exists, so return values need no explanation; the description instead covers the things structured fields cannot -- the three invocation modes, per-category cost coverage, and interpretation caveats for missing data. Nothing needed to call a zero-required-parameter tool correctly is missing.

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 parameter baseline is 3; the description exceeds it by grouping the nine parameters into three coherent modes and clarifying intent (e.g. together_required = no later add-on, partner = unmarried partner, not spouse). It adds orientation but no syntax beyond the schema's own examples.

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?

Starts with a specific verb+resource ('FAMILY PATHWAYS: who can come with, or join, the main applicant') and enumerates the exact dependent classes covered (spouse, partner, children, adult dependent children, parents, siblings). A reader can distinguish it from siblings like find_pathways or compare_programmes 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?

Explicitly decomposes usage into three modes and names the parameter that selects each (programme_id, cc, screen), with worked examples (antigua-cbi, PT, children_ages [7,15,24]). It lacks any explicit exclusion or pointer to a sibling tool for the adjacent question (e.g. general pathway discovery vs. family-specific pathways), so it stops short of a 5.

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