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

Annotations already cover read-only/idempotent/open-world, so the bar is lower; the description adds real substance about the return payload (published 360Giving totals, open/rolling/forthcoming/recently closed schemes with URLs). It omits pagination, rate limits and empty-result behavior, but is well beyond the annotation baseline.

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 action verb, then a dense but relevant enumeration of return fields, followed by lookup-key guidance. No filler, though the returned-field list is long enough to be slightly weighty.

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 no output schema, the description carries the full burden of explaining return contents and it does so thoroughly, plus it explains the multi-key lookup semantics. An agent has everything needed to call and interpret this tool.

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 adds meaning by tying slug to a funderUrl source and clarifying that a name query is fuzzy and may return multiple closest matches. That fuzzy-match behavior is not in the schema.

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?

Specific verb (Read) plus precise resource (a UK funder's public profile), and it enumerates exactly what is returned (type, numbers, website, income, 360Giving totals, schemes). It is clearly distinct from the sibling grant-retrieval tools.

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?

States the three lookup keys (OpenGrant slug, charity number, name) and the fallback behavior for ambiguous names ('returns the closest matches if there is more than one'). No explicit when-not guidance or named alternatives, but the usage context is unambiguous.

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