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

Annotations already declare the read-only, idempotent, non-destructive, closed-world profile, so the safety bar is covered. The description adds genuine behavioral context beyond that: results are newest-first and each carries a plain-text body plus extracted operating metrics. It does not discuss pagination traversal or result-capping behavior, keeping it just under full marks.

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 tight sentences: the first front-loads what is listed and what is returned, the second covers filtering and id lookup. No filler, no restatement of the name, everything earns its place.

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 return-value burden and does so by naming the plain-text body and extracted operating metrics. Combined with fully-specified schema params and a complete annotation set, the definition is nearly self-sufficient, missing only notes on pagination response shape.

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 coverage is 100%, so the baseline is 3, but the description adds meaning the schema lacks: slugs come from list_companies/search_companies and the id is the value search returns for update hits. This disambiguates otherwise opaque string and integer params.

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 ('List investor updates (founder update emails)'), clarifies scope ('across the authenticated user's portfolio, newest first'), and defines the resource for an agent that may not know what an 'update' is. It also positions itself relative to siblings by naming search as the id source and list_companies/search_companies as slug sources.

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?

Explains the two usage modes clearly: filter by company slug and/or date range, or fetch a single update by id. It cross-references where ids and slugs come from (search, list_companies/search_companies), which is practical routing guidance. It stops short of explicit when-not-to-use framing, so it is clear context without exclusions.

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