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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false and an output schema exists, so the safety/return profile is covered elsewhere. The description adds only the interpretive framing that repeats, inversions and shared regions are what such plots reveal — nothing about cost, the max_cells ceiling, or which engine consumes which parameters.

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?

A single front-loaded sentence with zero filler, which is structurally clean. For a tool this configurable it is arguably too terse, but nothing is redundant or buried.

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 18 parameters, three mutually exclusive engines, and a nested subject object, the description never mentions that engine selection changes which parameters matter or what the result is (a plotted figure). The rich schema and output schema compensate, making this adequate rather than inadequate.

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 all 18 parameters — including the word/window/matrix engine gating and advanced flags — are already documented where the agent reads them. The description adds no meaning beyond the schema; 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?

The description states a specific verb (self-similarity or pairwise comparison) and resource (the subject), and names concrete outputs of interest — repeats, inversions, shared regions. It does not differentiate itself from the sibling dot_plot_grid, which an agent could easily confuse it with.

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?

It implicitly frames two modes — compare the subject to itself, or to a pairwise partner — which maps to leaving `other` unset or set. However there is no explicit when-to-use guidance, no exclusion against dot_plot_grid or alignment tools, and no note about which engine to pick for which question.

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