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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds real behavioral context beyond that, notably that the facts are 'each confirmed by the owner' (a data-provenance signal) and that the key list includes 'common keys still empty'. It does not describe the return shape in any structured way, which matters since there is no output schema.

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?

Three sentences, front-loaded with the read action, and the exclusion is saved for last as a routing cue. The middle sentence is a run-on that tries to cover two distinct outputs (custom facts and the key list) in one breath, and 'stub has no other field for' costs the reader a re-read.

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 and no parameters, the description carries the burden of explaining what comes back, and it does list the returned content (owner-confirmed facts, all keys used, empty common keys). Naming the excluded fields and where to get them closes the main gap. What is missing is any sense of the shape or size of the fact list.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. No misleading parameter claims are made.

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?

States a clear verb+resource ('Read the business's profile') and grounds it with concrete examples (accountant, B-BBEE level, CSD number, lease end) plus a second function, listing the business's keys. It distinguishes itself from the sibling get_business_profile by explicitly excluding VAT/registration/payroll numbers. The phrasing 'concrete facts stub has no other field for' is awkward jargon that slightly muddies an otherwise clear purpose.

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 routes the agent elsewhere for tax identifiers ('The VAT, registration and payroll numbers are not here: read them with get_business_profile'), which is exactly the kind of alternative-naming that prevents mis-selection. It also gives a rationale for the key listing ('so you reuse one rather than name a new one'). It stops short of a full when-to-use/when-not matrix against the other profile-ish siblings such as get_business_overview.

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