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

Annotations declare readOnlyHint=false and openWorldHint=true but say nothing about cost or provider gating; the description fills both gaps by disclosing ~200-500 credit charges on the paid provider, unavailability on the free provider, and the SEO_DATA_UNAVAILABLE error semantics. This is exactly the context annotations cannot carry.

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 purpose, then cost and provider caveats — an efficient ordering. The closing remark about the absent spam-score column is editorial and slightly expendable, but it does preempt an agent expecting that field.

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 still conveys the return shape (anchors with per-anchor counts), the billing model, provider availability, and the meaning of the SEO_DATA_UNAVAILABLE signal. Nothing needed to invoke or interpret the call 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 every parameter (page, scope, target, pageSize, sortField, sortOrder) is already documented. The description adds only loose hints ('one page at a time', 'domain or URL') and no format or default details beyond the schema, so 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?

States a specific verb+resource ('Anchor-text distribution for a domain or URL') and enumerates the payload per row (backlinks, referring domains, referring pages, dofollow). An agent can distinguish it from get_backlinks_overview or get_link_intersect without opening a 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?

Gives clear motivating context for when it matters: revealing an over-optimised or hacked profile that is 'invisible link by link'. It also flags non-availability on the free provider. It stops short of naming an alternative tool for anchor data, so it earns a 4 rather than a 5.

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