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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that results can be filtered by tag and what data fields are returned, which is useful. However, it never explicitly states that this is a read/retrieval operation, and it does not describe behavior for invalid filter keys or no-match scenarios. No contradiction exists since annotations are absent.

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 sentence packs in the subject, domain scope, returned fields, and filtering behavior without filler. The parenthetical list '(name, what it is best for, tags)' is slightly awkward mid-sentence, but every clause earns its place and the core message lands quickly.

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 2-parameter tool with no output schema and 0% parameter coverage, the description leaves material gaps: no explicit operation verb, no clear parameter mapping, and no differentiation from sibling comparison tools. An agent could guess the filter semantics, but guessing is exactly what a complete definition should prevent.

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 0%, so the description must compensate, but it only partially does. The phrase 'optionally filtered by a tag value' hints that filterValue holds a tag value, yet it never maps filterKey and filterValue to their roles, defines valid values, or clarifies whether filterKey is always the tag field. The two bare string parameters remain largely ambiguous.

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 identifies the resource (options in a UK telephone answering services comparison) and its contents (name, best-for, tags), plus the filtering capability. However, it lacks an explicit action verb — it describes what the options are rather than what the tool does with them (list? get?). The title 'The options' matches the opening words of the description, edging toward tautology, though the added domain context saves it from a lower score.

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?

No guidance is given on when to use this tool versus its siblings compare_criteria or compare_table. The only usage hint is 'optionally filtered by a tag value,' which conveys capability but not selection criteria, prerequisites, or exclusions. An agent must infer when this tool is the right choice.

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