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

Annotations already establish readOnlyHint=true and openWorldHint=false, and the description goes beyond them by disclosing that data is 'stored' (i.e., a cached snapshot), that dividends are excluded, and by decoding the `searches` status values — including the important nuance that 'complete' with an empty calendar is a real answer while 'failed' means unknown. That materially changes how an agent should interpret empty or partial results. It stops short of covering freshness/staleness or refresh behavior implied by 'unsearched'/'running'.

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?

Two sentences, front-loaded with the scope constraint before the status semantics. The parenthetical glosses ('an empty calendar is a real answer', 'still unknown') earn their place by preventing misinterpretation, though the second sentence is dense enough to require a re-read.

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 no output schema, the description carries the burden of describing returns, and it only explains the `searches` status field, not the shape of the catalyst records themselves. For a two-parameter read tool with a safety annotation this is adequate but leaves the agent guessing what a catalyst entry contains.

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?

Neither parameter is addressed in the description: `symbols` (the required array, with its ticker pattern and 20-item cap) gets no mention, and `horizonDays` is documented only in the schema. Schema coverage is 50%, so the description should be compensating for the undocumented `symbols` parameter but does not.

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 names the resource precisely ('upcoming catalysts') and draws a scope boundary ('excludes dividends'), which no sibling name suggests. It lacks an explicit verb (the read is only implied by 'Stored'), so it is clear but slightly less crisp than a verb+resource statement.

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?

There is no statement of when to call this versus the sibling read_* tools, no prerequisites, and no mention of when-not to use it. The only orienting information is about interpreting the result, not about selecting the tool.

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