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

Annotations already declare readOnlyHint, idempotentHint and a closed-world scope, so safety is covered. Beyond that, the description discloses genuinely useful behavior: the Rust-first ordering, that `rust` is null and `lead` becomes "react" when no Rust exists, that former nyuchi-* names resolve to mzizi-* successors, and that React is maintained but deprioritised. It omits only edge cases such as what happens when the component name is unknown.

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-loaded with the core action and the Rust-first rationale, and every clause carries information about the return shape rather than filler. It is dense and slightly repetitive in restating the rust/react fields, but no sentence is wasted.

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 available, the description does the heavy lifting by describing the return structure field-by-field (rust/react, lead, files[], CONTRACT clause, npx line). It is nearly self-sufficient for a two-parameter read tool; the only gap is error/not-found behavior, which is minor.

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 adds meaning the schema does not: `include` pulls in docs (use cases, variants, a11y contract) and version history, and explicitly notes that omitting it returns implementations only. It also clarifies that `name` accepts legacy nyuchi-* aliases, which is not in 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?

States a specific verb (fetch) and resource (one component) and immediately distinguishes itself from the sibling list tool by scoping to a single component fetched 'in full'. It goes further by naming the exact shape of what comes back (rust crate, cargo add line, CONTRACT block, .rs source, then the react build), so an agent knows precisely what this returns versus mzizi_list_components.

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 explains the conditional behavior (Rust-first when a Roots implementation exists, React deprioritised otherwise) and when to use `include`, which is useful implied usage guidance. However, it never explicitly names an alternative tool or states a when-not condition, leaving the agent to infer that mzizi_list_components is the browsing counterpart.

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