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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the agent knows this is a pure, side-effect-free computation. The description adds no behavioral context beyond that: it does not say whether the brand value is included in the total denominator, whether all values must share the same metric/period, or what form the result takes.

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 that leads with the verb and resource before listing scope. Every clause carries information; there is no filler or repetition of the title.

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 four-parameter computation with no output schema, the description should say what comes back (a percentage share, presumably) and confirm how the denominator is formed. It covers the input domain well but leaves the result shape entirely unspecified.

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 only 25% (only 'metric' is documented), so the description must partially compensate. 'Brand against competitors' and 'on any metric' imply that brand_value and each competitor's value are counts measured on that same metric, which helps. However, it never addresses the 20-competitor cap, the non-negative constraint, or the required-vs-optional split.

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 and resource ('Calculates share of voice') and immediately scopes it ('for a brand against competitors'), then enumerates supported metric domains (AI citations, search impressions, ad impressions, social mentions, press coverage). No sibling tool computes share of voice, so an agent can distinguish it from the other calculators without opening the 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?

The 'on any metric' phrasing implies broad applicability but never states when to choose this over alternatives (e.g. roas_check, engagement_rate, acos_check) or when it is inappropriate. Usage is inferable from the purpose statement rather than explicitly guided.

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