repo_summary

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

Rich annotations (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false) already carry the safety profile, so the bar is lower. The description adds one genuinely useful behavioral detail, that the branch data reflects the currently checked-out branch and the extension distribution is computed at HEAD, but says nothing about cost, caching, or behavior on large/empty repos.

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?

A single sentence, front-loaded with the scope ('Overview of a repository') followed by a tight enumeration of outputs; there is no filler. The field list is slightly long and partly overlaps the output schema, which keeps it just short of a 5.

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?

An output schema exists, so return values need not be spelled out, annotations cover the read-only/idempotent profile, and the single parameter is fully documented in the schema. For a low-complexity one-argument aggregate query, nothing an agent needs in order to call it correctly is missing.

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?

There is one parameter and schema description coverage is 100%; the schema already explains that 'repo' is a repository alias pointing at the git-insights://repos resource. The description adds no additional parameter meaning, so the baseline 3 applies.

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 states a specific resource ('a repository') and enumerates exactly what is produced: checked-out branch, commit count, first/last commit dates, authors by commit count, and file-extension distribution. This content scope cleanly separates it from the per-author sibling (author_activity) and the per-file/analysis siblings (hotspots, file_history, coupled_files), so an agent can route to it without opening a 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?

The description is purely a content inventory; it never says when to reach for this overview versus running author_activity, hotspots, or coupled_files for a narrower question, and it states no prerequisites. Only the implicit 'reach for this when you want a repo-level overview' signal is present, which is minimal guidance.

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