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

Annotations already cover read-only, idempotent, non-destructive and closed-world safety. The description adds genuinely new behavior: output is grouped counts per stage, and data completeness depends on the account plan (full records vs. outline). That plan-gated read behavior is not derivable from annotations or schema and is valuable for interpreting results.

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?

Front-loads the trigger ('Use this when...'), then behavior, then a worked example, then the plan caveat. Efficient overall, though the final sentence about account plans is dense and could be tightened.

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 an 11-param, zero-required tool with no output schema, the description covers what is returned (grouped counts per stage) and the important plan-dependent completeness caveat. It is complete enough to call correctly, with only minor gaps in describing pagination/limit behavior, which the schema already documents.

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. The description earns above baseline by explaining cross-parameter interaction the schema cannot ('by=target with indication=obesity counts the targets of obesity programmes') and by naming the grouping values the `by` enum offers.

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 (counts) and resource (drug and therapy programmes/pipeline), and enumerates the grouping dimensions it supports. It also positions itself against sibling list_assets by noting it 'takes list_assets' filters', making the count-vs-list distinction explicit without opening either 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?

'Use this when the user asks how many...' gives a clear trigger condition, and the list_assets filter reference points to the sibling it complements. It stops short of an explicit when-not (e.g., 'use list_assets instead when you need the full records'), so it's strong but not fully routed.

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