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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds behavioral detail about the default phase, the 95 free dofollow rows, and what each row contains (submission page and recorded listing for projects), which goes beyond the annotations and enriches the agent's understanding of the output.

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?

The description is two sentences with no fluff. It front-loads the core purpose and then gives essential output details. Every word earns its place, and it avoids repeating schema 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?

For a list tool with 6 optional parameters and no output schema, the description covers the key behavioral aspects: default phase, row content, and per-project recorded listings. It doesn't explicitly describe ordering or pagination, but those are handled by schema fields (offset, limit) and the phrase 'in the order that works' provides a hint. Overall, it's complete enough for an agent to call it correctly.

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 coverage is 100%—every parameter has a description. The tool description adds context about the default phase and what rows contain, which indirectly relates to the phase and unrecorded_only parameters, but it does not need to explain each parameter since the schema already does. This meets the baseline for high schema coverage.

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 clearly identifies the tool as listing directories that provide backlinks, and it specifies the output includes submission pages and recorded listings. It is distinguishable from siblings like get_directory (singular) and next_steps, though it doesn't explicitly use the word 'list'—the name covers that.

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?

The description explains the phase-based workflow ('one phase at a time') and the default phase, which gives context for how to use the tool. However, it does not contrast this with alternatives like get_directory or when to choose this over other tools, so usage guidance is implied rather than explicit.

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