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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond these: it explains the provisional combined view during the newest quarter's filing window, including the carry-forward of prior-quarter positions and that this is flagged in the output. This is exactly the kind of nuance an agent needs to interpret the data correctly. No contradictions with annotations.

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 three sentences, each adding value: the purpose and output, the provisional-quarter behavior, and the intended use case. It is front-loaded with the primary action and resource. It is efficient with no filler, though it could be tightened slightly if desired. Deserves a 4 for good structure without waste.

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 read-only tool with two parameters and no output schema, the description covers the essential context: what data is returned, the time dimension, and the special provisional-quarter caveat. It does not specify the exact response format, but given the tool's simplicity and the presence of annotations for safety, this is adequate. Missing a few details like specific output fields (though some are mentioned) keeps it from a 5, but it is otherwise complete.

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?

The input schema provides full descriptions for both parameters: ticker (example usage) and maxPeriods (default and clamp range). Since schema description coverage is 100%, the description does not need to re-explain these and indeed does not add any additional meaning. The baseline of 3 is appropriate because the description adds nothing beyond the schema.

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 states the tool retrieves the historical trend of institutional ownership across multiple quarters, specifying the resource (institutional ownership) and the dimension (trend over time). It also lists the key output fields (total shares, market value, holder count). However, it does not explicitly name sibling tools or differentiate from them by name, though the 'historical trend' scope distinguishes it from related tools like GetInstitutionQuarterlyActivity or GetTopHolders. Missing explicit sibling differentiation keeps it at 4 rather than 5.

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 gives a clear use case: 'Use this to understand whether institutional interest in a company is growing or declining.' This tells the agent when the tool is appropriate. It does not mention explicit alternatives or exclusions (e.g., 'for a single quarter use X'), so it lacks the when-not-to-use guidance that would earn a 5. The context is clear but not exhaustive.

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